Disclosed is a fat accumulation suppressor comprising a whey protein hydrolysate having an excellent fat accumulation suppressing effect as an active ingredient.Specifically disclosed is a fat accumulation suppressor comprising a whey protein hydrolysate having a molecular weight distribution of 10 kDa or less wherein the main peak appears in a range from 200 to 3 kDa, and which has an APL (average peptide length) of 2 to 8, a free amino acid content of 20% or less and a branched amino acid content of 20% or more both relative to the total amount of all of the components, and an antigenicity lower by 1/100,000 than that of β-lactoglobulin.
