Civista Bancshares (CIVB) 10-Q 2018 Q1 Quarterly report

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 Quarterly Report of Civista Bancshares, Inc. (the “Company”) on Form 10-Q for the period ending March 31, 2018 as filed with the Securities and Exchange Commission on the date of this certification (the “Report”), I, Dennis G. Shaffer, 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 results of operations of the Company.

/s/ Dennis G. Shaffer

Dennis G. Shaffer

Chief Executive Officer

May 10, 2018