ROCKY HILL, Conn. (AP) _ Herbert Gilman, chairman and a founder of Ames Department Stores Inc., will retire early next year, the company announced Monday.

Gilman will be succeeded by James A. Harmon, chairman of Wertheim Schroder & Co., who is currently chairman of Ames' executive committee, the company said in a statement.

''Under the leadership of Herbert Gilman, Ames has become one of the nation's leading retailers,'' said Peter B. Hollis, Ames' chief executive officer.

Gilman will retired as of Jan. 31, 1988, but will remain a director of the company, which operates 343 discount department stores and 144 variety stores.