A skin whitening agent comprising, as the active ingredient, a complex ofcarbonic acid and/orbicarbonic acid, a metal and a lactoferrin (LF), a decomposition product ofthe complex, or acomplex of carbonic acid and/or bicarbonic acid, a metal and a decompositionproduct of alactoferrin (LF); and a food, beverage, feed or cosmetic comprising the skinwhitening agent.The skin whitening agent can be ingested safely on a daily basis, and exhibitsan excellent skinwhitening effect.