The Hanover Insurance Group, Inc. (THG) 10-Q 2017 Q3 Quarterly report

Exhibit 32.1

CERTIFICATION PURSUANT TO

SECTION 1350, CHAPTER 63 OF TITLE 18, UNITED STATES CODE,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

Pursuant to Section 1350, Chapter 63 of Title 18, United States Code, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, the undersigned, as President, Chief Executive Officer and Director of The Hanover Insurance Group, Inc. (the “Company”), does hereby certify that to the undersigned’s knowledge:

1) the Company’s Quarterly Report on Form 10-Q for the period ended September 30, 2017 (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 Company’s Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

/s/ Joseph M. Zubretsky

Joseph M. Zubretsky

President, Chief Executive Officer

and Director

Dated: November 2, 2017