Provided is a preparation for use on the skin, said preparation having the effect of markedly promoting collagen production in skin fibroblasts. An active ingredient of said preparation is a ?-glutamyl transpeptidase inhibitor that decreases the amount of glutathione in skin fibroblasts. Also provided is a preparation for use on the skin, said preparation reducing damage from ultraviolet radiation. Further provided is a preparation for use on the skin, said preparation improving moisture retention.