EXHIBIT 32.1

CERTIFICATION 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 Annual Report of Jabil Circuit, Inc. (the “Company”) on Form 10-K for the fiscal year ended August 31, 2006 as filed with the Securities and Exchange Commission on the date hereof (the “Form 10-K”), I, Timothy L. Main, President and Chief Executive Officer of the Company, hereby certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:

(1) The Form 10-K fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934 (15 U.S.C. 78m or 78o(d)); and

(2) The information contained in the Form 10-K fairly presents, in all material respects, the financial condition and results of operations of the Company.

Date: May 15, 2007

/s/    TIMOTHY L. MAIN        

Timothy L. Main

President and Chief Executive Officer