PURPOSE: To obtain the compsn. which releases an effective component at a controlled rate by mixing the effective component into a mixture comprising a polyester obtd. by a specific reaction and an acrylic polymer.

CONSTITUTION: The compsn. is obtd. by mixing a low-molecular effective component (e.g. isoamyl isovalerate) into a mixture comprising 5-100 pts.wt. polyester obtd. by reacting a hydroxyl compd. (e.g. a compd. having at least two OH groups, a compd. having OH and COOH groups, or a compd. having OH and NH2 groups), a cyclic acid anhydride, and an epoxide and 5-100 pts.wt. acrylic polymer (e.g. a hydroxylated acrylic polymer, a carboxylated acrylic polymer, or an aminated acrylic polymer). Thus, the rate of release of the effective component can be controlled without impairing the excellent properties of polymer material.