To provide a resin composition which can retain an insect pest control agent at a high concentration. The resin composition comprises a component (A), a component (B) and a component (C), the content of the component (A) is from 1 to 99% by weight, wherein the content of the component (B) is from 99 to 1% by weight, provided that the total amount of the component (A) and the component (B) is let be 100% by weight, and the content of the component (C) is from 1.5 to 50 parts by weight, provided that the total amount of the component (A) and the component (B) is let be 100 parts by weight, and the components (A), (B) and (C) are as follows: component (A): non-crystalline or low crystalline olefin-based polymer as a polymer having a monomer unit derived from olefin with which neither a crystal fusion peak having a heat of crystal fusion of 30 J/g or more, nor a crystallization peak having a heat of crystallization of 30 J/g or more are observed at a range of -50 to 200 C by differential scanning calorimetry according to JIS K 7122, compound (B): a crystalline propylene-based polymer, and component (C): an insect pest control agent.