Exhibit 24

DIRECTOR’S POWER OF ATTORNEY

(2003 Form 10-K)

The undersigned director of Marshall & Ilsley Corporation designates each of Dennis J. Kuester, 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 Form 10-K for the fiscal year ended December 31, 2003 and any related amendments and/or supplements; (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, 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 10-K and any related amendments and/or supplements.

Dated this 19th day of February, 2004.

/s/ Richard A. Abdoo

Richard A. Abdoo

DIRECTOR’S POWER OF ATTORNEY

(2003 Form 10-K)

The undersigned director of Marshall & Ilsley Corporation designates each of Dennis J. Kuester, 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 Form 10-K for the fiscal year ended December 31, 2003 and any related amendments and/or supplements; (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, 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 10-K and any related amendments and/or supplements.

Dated this 19th day of February, 2004.

/s/ David L. Andreas

David L. Andreas

DIRECTOR’S POWER OF ATTORNEY

(2003 Form 10-K)

The undersigned director of Marshall & Ilsley Corporation designates each of Dennis J. Kuester, 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 Form 10-K for the fiscal year ended December 31, 2003 and any related amendments and/or supplements; (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, 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 10-K and any related amendments and/or supplements.

Dated this 26th day of February, 2004.

/s/ Andrew N. Baur

Andrew N. Baur

DIRECTOR’S POWER OF ATTORNEY

(2003 Form 10-K)

The undersigned director of Marshall & Ilsley Corporation designates each of Dennis J. Kuester, 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 Form 10-K for the fiscal year ended December 31, 2003 and any related amendments and/or supplements; (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, 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 10-K and any related amendments and/or supplements.

Dated this 26th day of February, 2004.

/s/ Jon F. Chait

Jon F. Chait

DIRECTOR’S POWER OF ATTORNEY

(2003 Form 10-K)

The undersigned director of Marshall & Ilsley Corporation designates each of Dennis J. Kuester, 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 Form 10-K for the fiscal year ended December 31, 2003 and any related amendments and/or supplements; (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, 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 10-K and any related amendments and/or supplements.

Dated this 19th day of February, 2004.

/s/ Bruce E. Jacobs

Bruce E. Jacobs

DIRECTOR’S POWER OF ATTORNEY

(2003 Form 10-K)

The undersigned director of Marshall & Ilsley Corporation designates each of Dennis J. Kuester, 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 Form 10-K for the fiscal year ended December 31, 2003 and any related amendments and/or supplements; (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, 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 10-K and any related amendments and/or supplements.

Dated this 19th day of February, 2004.

/s/ Donald R. Johnson

Donald R. Johnson

DIRECTOR’S POWER OF ATTORNEY

(2003 Form 10-K)

The undersigned director of Marshall & Ilsley Corporation designates each of Dennis J. Kuester, 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 Form 10-K for the fiscal year ended December 31, 2003 and any related amendments and/or supplements; (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, 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 10-K and any related amendments and/or supplements.

Dated this 19th day of February, 2004.

/s/ Ted D. Kellner

Ted D. Kellner

DIRECTOR’S POWER OF ATTORNEY

(2003 Form 10-K)

The undersigned director of Marshall & Ilsley Corporation designates each of Dennis J. Kuester, 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 Form 10-K for the fiscal year ended December 31, 2003 and any related amendments and/or supplements; (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, 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 10-K and any related amendments and/or supplements.

Dated this 19th day of February, 2004.

/s/ Dennis J. Kuester

Dennis J. Kuester

DIRECTOR’S POWER OF ATTORNEY

(2003 Form 10-K)

The undersigned director of Marshall & Ilsley Corporation designates each of Dennis J. Kuester, 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 Form 10-K for the fiscal year ended December 31, 2003 and any related amendments and/or supplements; (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, 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 10-K and any related amendments and/or supplements.

Dated this 24th day of February, 2004.

/s/ Katharine C. Lyall

Katharine C. Lyall

DIRECTOR’S POWER OF ATTORNEY

(2003 Form 10-K)

The undersigned director of Marshall & Ilsley Corporation designates each of Dennis J. Kuester, 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 Form 10-K for the fiscal year ended December 31, 2003 and any related amendments and/or supplements; (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, 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 10-K and any related amendments and/or supplements.

Dated this 19th day of February, 2004.

/s/ Edward L. Meyer, Jr.

Edward L. Meyer, Jr.

DIRECTOR’S POWER OF ATTORNEY

(2003 Form 10-K)

The undersigned director of Marshall & Ilsley Corporation designates each of Dennis J. Kuester, 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 Form 10-K for the fiscal year ended December 31, 2003 and any related amendments and/or supplements; (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, 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 10-K and any related amendments and/or supplements.

Dated this 19th day of February, 2004.

/s/ San W. Orr, Jr.

San W. Orr, Jr.

DIRECTOR’S POWER OF ATTORNEY

(2003 Form 10-K)

The undersigned director of Marshall & Ilsley Corporation designates each of Dennis J. Kuester, 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 Form 10-K for the fiscal year ended December 31, 2003 and any related amendments and/or supplements; (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, 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 10-K and any related amendments and/or supplements.

Dated this 24th day of February, 2004.

/s/ Robert J. O’Toole

Robert J. O’Toole

DIRECTOR’S POWER OF ATTORNEY

(2003 Form 10-K)

The undersigned director of Marshall & Ilsley Corporation designates each of Dennis J. Kuester, 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 Form 10-K for the fiscal year ended December 31, 2003 and any related amendments and/or supplements; (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, 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 10-K and any related amendments and/or supplements.

Dated this 19th day of February, 2004.

/s/ Peter M. Platten, III

Peter M. Platten, III

DIRECTOR’S POWER OF ATTORNEY

(2003 Form 10-K)

The undersigned director of Marshall & Ilsley Corporation designates each of Dennis J. Kuester, 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 Form 10-K for the fiscal year ended December 31, 2003 and any related amendments and/or supplements; (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, 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 10-K and any related amendments and/or supplements.

Dated this 19th day of February, 2004.

/s/ Robert A. Schaefer

Robert A. Schaefer

DIRECTOR’S POWER OF ATTORNEY

(2003 Form 10-K)

The undersigned director of Marshall & Ilsley Corporation designates each of Dennis J. Kuester, 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 Form 10-K for the fiscal year ended December 31, 2003 and any related amendments and/or supplements; (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, 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 10-K and any related amendments and/or supplements.

Dated this 26th day of February, 2004.

/s/ John S. Shiely

John S. Shiely

DIRECTOR’S POWER OF ATTORNEY

(2003 Form 10-K)

The undersigned director of Marshall & Ilsley Corporation designates each of Dennis J. Kuester, 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 Form 10-K for the fiscal year ended December 31, 2003 and any related amendments and/or supplements; (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, 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 10-K and any related amendments and/or supplements.

Dated this 19th day of February, 2004.

/s/ James A. Urdan

James A. Urdan

DIRECTOR’S POWER OF ATTORNEY

(2003 Form 10-K)

The undersigned director of Marshall & Ilsley Corporation designates each of Dennis J. Kuester, 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 Form 10-K for the fiscal year ended December 31, 2003 and any related amendments and/or supplements; (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, 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 10-K and any related amendments and/or supplements.

Dated this 19th day of February, 2004.

/s/ George E. Wardeberg

George E. Wardeberg

DIRECTOR’S POWER OF ATTORNEY

(2003 Form 10-K)

The undersigned director of Marshall & Ilsley Corporation designates each of Dennis J. Kuester, 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 Form 10-K for the fiscal year ended December 31, 2003 and any related amendments and/or supplements; (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, 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 10-K and any related amendments and/or supplements.

Dated this 19th day of February, 2004.

/s/ James B. Wigdale

James B. Wigdale

DIRECTOR’S POWER OF ATTORNEY

(2003 Form 10-K)

The undersigned director of Marshall & Ilsley Corporation designates each of Dennis J. Kuester, 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 Form 10-K for the fiscal year ended December 31, 2003 and any related amendments and/or supplements; (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, 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 10-K and any related amendments and/or supplements.

Dated this 19th day of February, 2004.

/s/    John A. Mellowes        

John A. Mellowes