Exhibit 32.2

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 October 31, 2012 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, William J. Walljasper, Chief Financial 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 results of operations of the Company.

/s/ William J. Walljasper

William J. Walljasper

Senior Vice President and Chief Financial Officer

December 10, 2012