PURPOSE: To enable to increase duration time of moth-proofing effect of a moth proofing agent composed mainly of para-dichlorobenzene and to reduce amount of the moth-proofing agent itself.

CONSTITUTION: One or more kinds of oils selected from white cedar oil and Japanese cypress oil are used as the essential component and blended in an amount of 0.5 to 15wt.% with para-dichlorobenzene. If the amount of the used moth-proofing agent in within the range of a standard amount, the moth-proofing activity can be effectively and stably exhibited for a long period. Even in the case where the amount of the moth-proofing agent is increased so as to keep effective moth-proofing activity for a long period, the fault, i.e., adhesion of strong stimulating odor from para-dichlorobenzene can be dissolved.