Exhibit 24

DIRECTOR’S POWER OF ATTORNEY

(Form S-4 Relating to the Proposed Merger of Gold Banc Corporation, Inc. with and into

Marshall & Ilsley Corporation)

The undersigned director of Marshall & Ilsley Corporation designates each of Mark F. Furlong and Randall J. Erickson, with the power of substitution, as his true and lawful attorney-in-fact for the purpose of: (i) executing in his name and on his behalf Marshall & Ilsley Corporation’s Registration Statement on Form S-4 relating to the proposed merger of Gold Banc Corporation, Inc. with and into Marshall & Ilsley Corporation and any related amendments (including post-effective amendments) and/or supplements to said Form S-4 (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended); (ii) generally doing all things in his name and on his behalf in his capacity as a director to enable Marshall & Ilsley Corporation to comply with the provisions of the Securities Exchange Act of 1934, as amended, the Securities Act of 1933, as amended, and all requirements of the Securities and Exchange Commission; and (iii) ratifying and confirming his signature as it may be signed by the attorney-in-fact to the Form S-4 and any related amendments (including post-effective amendments) and/or supplements thereto (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended).

Dated this 21^st day of November, 2005.

/s/    RICHARD A. ABDOO        

Richard A. Abdoo

DIRECTOR’S POWER OF ATTORNEY

(Form S-4 Relating to the Proposed Merger of Gold Banc Corporation, Inc. with and into

Marshall & Ilsley Corporation)

The undersigned director of Marshall & Ilsley Corporation designates each of Mark F. Furlong and Randall J. Erickson, with the power of substitution, as his true and lawful attorney-in-fact for the purpose of: (i) executing in his name and on his behalf Marshall & Ilsley Corporation’s Registration Statement on Form S-4 relating to the proposed merger of Gold Banc Corporation, Inc. with and into Marshall & Ilsley Corporation and any related amendments (including post-effective amendments) and/or supplements to said Form S-4 (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended); (ii) generally doing all things in his name and on his behalf in his capacity as a director to enable Marshall & Ilsley Corporation to comply with the provisions of the Securities Exchange Act of 1934, as amended, the Securities Act of 1933, as amended, and all requirements of the Securities and Exchange Commission; and (iii) ratifying and confirming his signature as it may be signed by the attorney-in-fact to the Form S-4 and any related amendments (including post-effective amendments) and/or supplements thereto (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended).

Dated this 17^th day of November, 2005.

/s/    ANDREW N. BAUR        

Andrew N. Baur

DIRECTOR’S POWER OF ATTORNEY

(Form S-4 Relating to the Proposed Merger of Gold Banc Corporation, Inc. with and into

Marshall & Ilsley Corporation)

The undersigned director of Marshall & Ilsley Corporation designates each of Mark F. Furlong and Randall J. Erickson, with the power of substitution, as his true and lawful attorney-in-fact for the purpose of: (i) executing in his name and on his behalf Marshall & Ilsley Corporation’s Registration Statement on Form S-4 relating to the proposed merger of Gold Banc Corporation, Inc. with and into Marshall & Ilsley Corporation and any related amendments (including post-effective amendments) and/or supplements to said Form S-4 (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended); (ii) generally doing all things in his name and on his behalf in his capacity as a director to enable Marshall & Ilsley Corporation to comply with the provisions of the Securities Exchange Act of 1934, as amended, the Securities Act of 1933, as amended, and all requirements of the Securities and Exchange Commission; and (iii) ratifying and confirming his signature as it may be signed by the attorney-in-fact to the Form S-4 and any related amendments (including post-effective amendments) and/or supplements thereto (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended).

Dated this 22^nd day of November, 2005.

/s/    JON F. CHAIT        

Jon F. Chait

DIRECTOR’S POWER OF ATTORNEY

(Form S-4 Relating to the Proposed Merger of Gold Banc Corporation, Inc. with and into

Marshall & Ilsley Corporation)

The undersigned director of Marshall & Ilsley Corporation designates each of Mark F. Furlong and Randall J. Erickson, with the power of substitution, as his true and lawful attorney-in-fact for the purpose of: (i) executing in his name and on his behalf Marshall & Ilsley Corporation’s Registration Statement on Form S-4 relating to the proposed merger of Gold Banc Corporation, Inc. with and into Marshall & Ilsley Corporation and any related amendments (including post-effective amendments) and/or supplements to said Form S-4 (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended); (ii) generally doing all things in his name and on his behalf in his capacity as a director to enable Marshall & Ilsley Corporation to comply with the provisions of the Securities Exchange Act of 1934, as amended, the Securities Act of 1933, as amended, and all requirements of the Securities and Exchange Commission; and (iii) ratifying and confirming his signature as it may be signed by the attorney-in-fact to the Form S-4 and any related amendments (including post-effective amendments) and/or supplements thereto (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended).

Dated this 15^th day of November, 2005.

/s/    JOHN W. DANIELS, JR.        

John W. Daniels, Jr.

DIRECTOR’S POWER OF ATTORNEY

(Form S-4 Relating to the Proposed Merger of Gold Banc Corporation, Inc. with and into

Marshall & Ilsley Corporation)

The undersigned director of Marshall & Ilsley Corporation designates each of Mark F. Furlong and Randall J. Erickson, with the power of substitution, as his true and lawful attorney-in-fact for the purpose of: (i) executing in his name and on his behalf Marshall & Ilsley Corporation’s Registration Statement on Form S-4 relating to the proposed merger of Gold Banc Corporation, Inc. with and into Marshall & Ilsley Corporation and any related amendments (including post-effective amendments) and/or supplements to said Form S-4 (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended); (ii) generally doing all things in his name and on his behalf in his capacity as a director to enable Marshall & Ilsley Corporation to comply with the provisions of the Securities Exchange Act of 1934, as amended, the Securities Act of 1933, as amended, and all requirements of the Securities and Exchange Commission; and (iii) ratifying and confirming his signature as it may be signed by the attorney-in-fact to the Form S-4 and any related amendments (including post-effective amendments) and/or supplements thereto (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended).

Dated this 15^th day of November, 2005.

/s/    BRUCE E. JACOBS        

Bruce E. Jacobs

DIRECTOR’S POWER OF ATTORNEY

(Form S-4 Relating to the Proposed Merger of Gold Banc Corporation, Inc. with and into

Marshall & Ilsley Corporation)

The undersigned director of Marshall & Ilsley Corporation designates each of Mark F. Furlong and Randall J. Erickson, with the power of substitution, as his true and lawful attorney-in-fact for the purpose of: (i) executing in his name and on his behalf Marshall & Ilsley Corporation’s Registration Statement on Form S-4 relating to the proposed merger of Gold Banc Corporation, Inc. with and into Marshall & Ilsley Corporation and any related amendments (including post-effective amendments) and/or supplements to said Form S-4 (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended); (ii) generally doing all things in his name and on his behalf in his capacity as a director to enable Marshall & Ilsley Corporation to comply with the provisions of the Securities Exchange Act of 1934, as amended, the Securities Act of 1933, as amended, and all requirements of the Securities and Exchange Commission; and (iii) ratifying and confirming his signature as it may be signed by the attorney-in-fact to the Form S-4 and any related amendments (including post-effective amendments) and/or supplements thereto (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended).

Dated this 17^th day of November, 2005.

/s/    TED D. KELLNER        

Ted D. Kellner

DIRECTOR’S POWER OF ATTORNEY

(Form S-4 Relating to the Proposed Merger of Gold Banc Corporation, Inc. with and into

Marshall & Ilsley Corporation)

The undersigned director of Marshall & Ilsley Corporation designates each of Mark F. Furlong and Randall J. Erickson, with the power of substitution, as his true and lawful attorney-in-fact for the purpose of: (i) executing in his name and on his behalf Marshall & Ilsley Corporation’s Registration Statement on Form S-4 relating to the proposed merger of Gold Banc Corporation, Inc. with and into Marshall & Ilsley Corporation and any related amendments (including post-effective amendments) and/or supplements to said Form S-4 (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended); (ii) generally doing all things in his name and on his behalf in his capacity as a director to enable Marshall & Ilsley Corporation to comply with the provisions of the Securities Exchange Act of 1934, as amended, the Securities Act of 1933, as amended, and all requirements of the Securities and Exchange Commission; and (iii) ratifying and confirming his signature as it may be signed by the attorney-in-fact to the Form S-4 and any related amendments (including post-effective amendments) and/or supplements thereto (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended).

Dated this 15^th day of November, 2005.

/s/    DENNIS J. KUESTER        

Dennis J. Kuester

DIRECTOR’S POWER OF ATTORNEY

(Form S-4 Relating to the Proposed Merger of Gold Banc Corporation, Inc. with and into

Marshall & Ilsley Corporation)

The undersigned director of Marshall & Ilsley Corporation designates each of Mark F. Furlong and Randall J. Erickson, with the power of substitution, as her true and lawful attorney-in-fact for the purpose of: (i) executing in her name and on her behalf Marshall & Ilsley Corporation’s Registration Statement on Form S-4 relating to the proposed merger of Gold Banc Corporation, Inc. with and into Marshall & Ilsley Corporation and any related amendments (including post-effective amendments) and/or supplements to said Form S-4 (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended); (ii) generally doing all things in her name and on her behalf in her capacity as a director to enable Marshall & Ilsley Corporation to comply with the provisions of the Securities Exchange Act of 1934, as amended, the Securities Act of 1933, as amended, and all requirements of the Securities and Exchange Commission; and (iii) ratifying and confirming her signature as it may be signed by the attorney-in-fact to the Form S-4 and any related amendments (including post-effective amendments) and/or supplements thereto (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended).

Dated this 15^th day of November, 2005.

/s/    KATHARINE C. LYALL        

Katharine C. Lyall

DIRECTOR’S POWER OF ATTORNEY

(Form S-4 Relating to the Proposed Merger of Gold Banc Corporation, Inc. with and into

Marshall & Ilsley Corporation)

The undersigned director of Marshall & Ilsley Corporation designates each of Mark F. Furlong and Randall J. Erickson, with the power of substitution, as his true and lawful attorney-in-fact for the purpose of: (i) executing in his name and on his behalf Marshall & Ilsley Corporation’s Registration Statement on Form S-4 relating to the proposed merger of Gold Banc Corporation, Inc. with and into Marshall & Ilsley Corporation and any related amendments (including post-effective amendments) and/or supplements to said Form S-4 (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended); (ii) generally doing all things in his name and on his behalf in his capacity as a director to enable Marshall & Ilsley Corporation to comply with the provisions of the Securities Exchange Act of 1934, as amended, the Securities Act of 1933, as amended, and all requirements of the Securities and Exchange Commission; and (iii) ratifying and confirming his signature as it may be signed by the attorney-in-fact to the Form S-4 and any related amendments (including post-effective amendments) and/or supplements thereto (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended).

Dated this 22^nd day of November, 2005.

/s/    JOHN A. MELLOWES        

John A. Mellowes

DIRECTOR’S POWER OF ATTORNEY

(Form S-4 Relating to the Proposed Merger of Gold Banc Corporation, Inc. with and into

Marshall & Ilsley Corporation)

The undersigned director of Marshall & Ilsley Corporation designates each of Mark F. Furlong and Randall J. Erickson, with the power of substitution, as his true and lawful attorney-in-fact for the purpose of: (i) executing in his name and on his behalf Marshall & Ilsley Corporation’s Registration Statement on Form S-4 relating to the proposed merger of Gold Banc Corporation, Inc. with and into Marshall & Ilsley Corporation and any related amendments (including post-effective amendments) and/or supplements to said Form S-4 (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended); (ii) generally doing all things in his name and on his behalf in his capacity as a director to enable Marshall & Ilsley Corporation to comply with the provisions of the Securities Exchange Act of 1934, as amended, the Securities Act of 1933, as amended, and all requirements of the Securities and Exchange Commission; and (iii) ratifying and confirming his signature as it may be signed by the attorney-in-fact to the Form S-4 and any related amendments (including post-effective amendments) and/or supplements thereto (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended).

Dated this 17^th day of November, 2005.

/s/    EDWARD L. MEYER, JR.        

Edward L. Meyer, Jr.

DIRECTOR’S POWER OF ATTORNEY

(Form S-4 Relating to the Proposed Merger of Gold Banc Corporation, Inc. with and into

Marshall & Ilsley Corporation)

The undersigned director of Marshall & Ilsley Corporation designates each of Mark F. Furlong and Randall J. Erickson, with the power of substitution, as his true and lawful attorney-in-fact for the purpose of: (i) executing in his name and on his behalf Marshall & Ilsley Corporation’s Registration Statement on Form S-4 relating to the proposed merger of Gold Banc Corporation, Inc. with and into Marshall & Ilsley Corporation and any related amendments (including post-effective amendments) and/or supplements to said Form S-4 (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended); (ii) generally doing all things in his name and on his behalf in his capacity as a director to enable Marshall & Ilsley Corporation to comply with the provisions of the Securities Exchange Act of 1934, as amended, the Securities Act of 1933, as amended, and all requirements of the Securities and Exchange Commission; and (iii) ratifying and confirming his signature as it may be signed by the attorney-in-fact to the Form S-4 and any related amendments (including post-effective amendments) and/or supplements thereto (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended).

Dated this 15^th day of November, 2005.

/s/    SAN W. ORR, JR.        

San W. Orr, Jr.

DIRECTOR’S POWER OF ATTORNEY

(Form S-4 Relating to the Proposed Merger of Gold Banc Corporation, Inc. with and into

Marshall & Ilsley Corporation)

The undersigned director of Marshall & Ilsley Corporation designates each of Mark F. Furlong and Randall J. Erickson, with the power of substitution, as his true and lawful attorney-in-fact for the purpose of: (i) executing in his name and on his behalf Marshall & Ilsley Corporation’s Registration Statement on Form S-4 relating to the proposed merger of Gold Banc Corporation, Inc. with and into Marshall & Ilsley Corporation and any related amendments (including post-effective amendments) and/or supplements to said Form S-4 (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended); (ii) generally doing all things in his name and on his behalf in his capacity as a director to enable Marshall & Ilsley Corporation to comply with the provisions of the Securities Exchange Act of 1934, as amended, the Securities Act of 1933, as amended, and all requirements of the Securities and Exchange Commission; and (iii) ratifying and confirming his signature as it may be signed by the attorney-in-fact to the Form S-4 and any related amendments (including post-effective amendments) and/or supplements thereto (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended).

Dated this 15^th day of November, 2005.

/s/    ROBERT J. O’TOOLE        

Robert J. O’Toole

DIRECTOR’S POWER OF ATTORNEY

(Form S-4 Relating to the Proposed Merger of Gold Banc Corporation, Inc. with and into

Marshall & Ilsley Corporation)

The undersigned director of Marshall & Ilsley Corporation designates each of Mark F. Furlong and Randall J. Erickson, with the power of substitution, as his true and lawful attorney-in-fact for the purpose of: (i) executing in his name and on his behalf Marshall & Ilsley Corporation’s Registration Statement on Form S-4 relating to the proposed merger of Gold Banc Corporation, Inc. with and into Marshall & Ilsley Corporation and any related amendments (including post-effective amendments) and/or supplements to said Form S-4 (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended); (ii) generally doing all things in his name and on his behalf in his capacity as a director to enable Marshall & Ilsley Corporation to comply with the provisions of the Securities Exchange Act of 1934, as amended, the Securities Act of 1933, as amended, and all requirements of the Securities and Exchange Commission; and (iii) ratifying and confirming his signature as it may be signed by the attorney-in-fact to the Form S-4 and any related amendments (including post-effective amendments) and/or supplements thereto (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended).

Dated this 22^nd day of November, 2005.

/s/    PETER M. PLATTEN, III        

Peter M. Platten, III

DIRECTOR’S POWER OF ATTORNEY

(Form S-4 Relating to the Proposed Merger of Gold Banc Corporation, Inc. with and into

Marshall & Ilsley Corporation)

The undersigned director of Marshall & Ilsley Corporation designates each of Mark F. Furlong and Randall J. Erickson, with the power of substitution, as his true and lawful attorney-in-fact for the purpose of: (i) executing in his name and on his behalf Marshall & Ilsley Corporation’s Registration Statement on Form S-4 relating to the proposed merger of Gold Banc Corporation, Inc. with and into Marshall & Ilsley Corporation and any related amendments (including post-effective amendments) and/or supplements to said Form S-4 (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended); (ii) generally doing all things in his name and on his behalf in his capacity as a director to enable Marshall & Ilsley Corporation to comply with the provisions of the Securities Exchange Act of 1934, as amended, the Securities Act of 1933, as amended, and all requirements of the Securities and Exchange Commission; and (iii) ratifying and confirming his signature as it may be signed by the attorney-in-fact to the Form S-4 and any related amendments (including post-effective amendments) and/or supplements thereto (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended).

Dated this 16^th day of November, 2005.

/s/    JOHN S. SHIELY        

John S. Shiely

DIRECTOR’S POWER OF ATTORNEY

(Form S-4 Relating to the Proposed Merger of Gold Banc Corporation, Inc. with and into

Marshall & Ilsley Corporation)

The undersigned director of Marshall & Ilsley Corporation designates each of Mark F. Furlong and Randall J. Erickson, with the power of substitution, as his true and lawful attorney-in-fact for the purpose of: (i) executing in his name and on his behalf Marshall & Ilsley Corporation’s Registration Statement on Form S-4 relating to the proposed merger of Gold Banc Corporation, Inc. with and into Marshall & Ilsley Corporation and any related amendments (including post-effective amendments) and/or supplements to said Form S-4 (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended); (ii) generally doing all things in his name and on his behalf in his capacity as a director to enable Marshall & Ilsley Corporation to comply with the provisions of the Securities Exchange Act of 1934, as amended, the Securities Act of 1933, as amended, and all requirements of the Securities and Exchange Commission; and (iii) ratifying and confirming his signature as it may be signed by the attorney-in-fact to the Form S-4 and any related amendments (including post-effective amendments) and/or supplements thereto (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended).

Dated this 15^th day of November, 2005.

/s/    JAMES A. URDAN        

James A. Urdan

DIRECTOR’S POWER OF ATTORNEY

(Form S-4 Relating to the Proposed Merger of Gold Banc Corporation, Inc. with and into

Marshall & Ilsley Corporation)

The undersigned director of Marshall & Ilsley Corporation designates each of Mark F. Furlong and Randall J. Erickson, with the power of substitution, as his true and lawful attorney-in-fact for the purpose of: (i) executing in his name and on his behalf Marshall & Ilsley Corporation’s Registration Statement on Form S-4 relating to the proposed merger of Gold Banc Corporation, Inc. with and into Marshall & Ilsley Corporation and any related amendments (including post-effective amendments) and/or supplements to said Form S-4 (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended); (ii) generally doing all things in his name and on his behalf in his capacity as a director to enable Marshall & Ilsley Corporation to comply with the provisions of the Securities Exchange Act of 1934, as amended, the Securities Act of 1933, as amended, and all requirements of the Securities and Exchange Commission; and (iii) ratifying and confirming his signature as it may be signed by the attorney-in-fact to the Form S-4 and any related amendments (including post-effective amendments) and/or supplements thereto (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended).

Dated this 15^th day of November, 2005.

/s/    GEORGE E. WARDEBERG        

George E. Wardeberg

DIRECTOR’S POWER OF ATTORNEY

(Form S-4 Relating to the Proposed Merger of Gold Banc Corporation, Inc. with and into

Marshall & Ilsley Corporation)

The undersigned director of Marshall & Ilsley Corporation designates each of Mark F. Furlong and Randall J. Erickson, with the power of substitution, as his true and lawful attorney-in-fact for the purpose of: (i) executing in his name and on his behalf Marshall & Ilsley Corporation’s Registration Statement on Form S-4 relating to the proposed merger of Gold Banc Corporation, Inc. with and into Marshall & Ilsley Corporation and any related amendments (including post-effective amendments) and/or supplements to said Form S-4 (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended); (ii) generally doing all things in his name and on his behalf in his capacity as a director to enable Marshall & Ilsley Corporation to comply with the provisions of the Securities Exchange Act of 1934, as amended, the Securities Act of 1933, as amended, and all requirements of the Securities and Exchange Commission; and (iii) ratifying and confirming his signature as it may be signed by the attorney-in-fact to the Form S-4 and any related amendments (including post-effective amendments) and/or supplements thereto (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended).

Dated this 22^nd day of November, 2005.

/s/    JAMES B. WIGDALE        

James B. Wigdale