PURPOSE: To obtain the subject composition having improved storage stability and high-temperature processing stability, capable of keeping the effect over a long period and safe to men and beasts by compounding a mixture of a terpenoid compound monomer and its oligomer and a liquid antioxidant having a specific viscosity at a specific mixing ratio.

CONSTITUTION: The objective composition exhibiting excellent repelling effect widely on noxious organisms such as rat, mite, termite and mussel contains (A) 100 pts.wt. of a mixture of a terpenoid compound monomer (e.g. α-pinene- dipentene and allocymene) and its oligomer (having a polymerization degree of 2-7 and an average molecular weight of ≤1,000) and (B) 0.01-10 pts.wt. of a liquid antioxidant having a viscosity of 1-30,000 cps at 18°C. The addition of the component B suppresses the oxidative or thermal deterioration of the component A used as a repelling component. The component B is especially preferably a combination of a thioether compound with an aromatic sec amine compound or a phenol phosphite compound.