The invention addresses the problem of providing a skin-beautifying agent with beautifying effects such as skin beautification, prevention of rough skin, wrinkle prevention of reduced elasticity, etc, and a skin-beautifying product such as a cosmetic, food or drink, feed, medicine,etc, that contains said skin-beautifying agent. The skin-beautifying agent is characterized in containing a hydrolyzate of whey protein as an active ingredient. Using a whey protein hydrolyzate having the characteristic of a molecular weight distribution of 10 kDa or less, a main peak of 200 Da - 3 kDa, APL (average peptide length) of 2-8, free amino acid content of 20% or less, and a ß-lactoglobulin antigeniity of 1/10,000 or less, in particular, provides a skin-beautifying agent of low allergenicity and low bitterness.
