A skin-whitening agent offering an excellent whitening effect and beingeffective inpreventing and treating age spots, freckles, etc., where such skin-whiteningagent containsas its effective ingredient a whey protein hydrolyzate characterized by amolecular weightdistribution of 10 kDa or less, main peak of 200 Da to 3 kDa, APL (averagepeptide-chainlength) of 2 to 8, free amino acid content of 20% or less, and antigenicity ofone-tenthousandth of .beta.-lactoglobulin or less, as well as a cosmetic, drink orfood, feed,pharmaceutical preparation or other skin-whitening product containing suchskin-whitening agent.
