Exhibit 32(b)

                      CERTIFICATION OF PERIODIC REPORT
                      ________________________________


     I, John M. Presley, Chief Financial Officer of Marshall & Ilsley
Corporation (the "Company"), certify, pursuant to Section 906 of the
Sarbanes-Oxley Act of 2002, 18 U.S.C. Section 1350, that to my knowledge:

     (1)  the Quarterly Report on Form 10-Q of the Company for the
          quarterly period ended September 30, 2004 (the "Report") fully
          complies with the requirements of Section 13(a) or 15(d) of the
          Securities Exchange Act of 1934 (14 U.S.C. 78m or 78o(d)); and

     (2)  the information contained in the Report fairly presents, in all
          material respects, the financial condition and results of
          operations of the Company.

Dated:  November 9, 2004.


                              /s/ John M. Presley
                              _______________________________

                              John M. Presley
                              Chief Financial Officer
                              Marshall & Ilsley Corporation




This certification accompanies this Quarterly Report on Form 10-Q pursuant
to Section 906 of the Sarbanes-Oxley Act of 2002 and shall not be deemed
filed by Marshall & Ilsley Corporation for purposes of the Securities
Exchange Act of 1934.



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