Disclosed is an agent for preventing the reduction in the production of collagen, which comprises an enzymatically decomposed product of swallow's nest as an active ingredient, and is an agent for preventing the reduction in the production of collagen in a dermal fibroblast caused by the irradiation with an ultraviolet light. Specifically disclosed are: an excellent agent for preventing the reduction in the production of collagen in a dermal fibroblast, which can be produced with high efficiency and is highly safe； and an external preparation and a cosmetic, each of which comprises the agent.본 발명에 의한 콜라겐 생산 저하 억제제는, 연와의 효소 분해물을 유효 성분으로 하는, 진피 섬유아세포에서의 자외선 조사에 의한 콜라겐 생산 저하의 억제제이다. 본 발명에 따르면, 효율적으로 생산할 수 있으며, 안정성이 높고, 진피 섬유아세포에 있어서의 콜라겐 생산 저하가 우수한 억제제, 및 이를 포함하는 외용제 및 화장료가 제공된다.
