Resin compositions for controlling small animals which contain: (A) at least one resin selected from among polyamide resins and polyacetal resins; (B) at least one compound selected from among sulfonamide derivatives, sulfonate derivatives, phosphate derivatives, phosphagen derivatives, carboxamide derivatives and carboxylate derivatives; and (C) a chemical having an effect of controlling small animals. By using these resin compositions, it is possible to obtain members for controlling small animals which are sufficient in strength, heat resistance and chemical resistance for serving as various structural members and can exert the effect of controlling small animals over a long period of time.