To provide an elastase inhibitor and a skin external preparation or a cosmetic containing the elastase inhibitor as an active ingredient.

The elastase inhibitor includes, as an active ingredient, an extract of one or more plants selected from the group of plants belonging to the genus Blechnum in the family Blechnaceae and the genus Polystichum in the family Dryopteridaceae. The skin external preparation or the cosmetic contains the same. The elastase inhibitor inhibits the decomposition of elastin of a dermal extracellular matrix-constituting component to maintain dermal homeostasis and accordingly is useful in preventing and improving the change in skin external appearance such as the deterioration of skin elasticity, the disappearance of texture, sagging, and dark spots. Further, the elastase inhibitor is useful in preventing and improving the condition of atherosclerosis, rheumatoid arthritis and the like which are caused by the decomposition of elastin fibers by elastase. Furthermore, elastase has the possibility of taking part in hair-follicle formation, and accordingly the elastase inhibitor is also useful for controlling hair growth and hair restoration.