Exhibit 32.1

CERTIFICATE PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of Casey’s General Stores, Inc. (the “Company”) on Form 10-Q for the period ending July 31, 2004 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Ronald M. Lamb, Chief Executive Officer of the Company, certify, pursuant to 18 U.S.C. § 1350, as adopted pursuant to § 906 of the Sarbanes-Oxley Act of 2002, that:

(1) The Report fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

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

/s/    RONALD M. LAMB        

Ronald M. Lamb

Chief Executive Officer

September 8, 2004