A fat accumulation suppressor comprising as an active ingredient a whey protein hydrolysate is provided. The hydrolysate has a molecular weight range of no higher than 10 kDa and a main peak of molecular weight at 200 Da to 3 kDa； an APL (average peptide chain length) of 2 to 8； a free amino acid content of 20% or lower； a branched chain amino acid content of 20% or higher； and an antigenicity of 1/100,000 or lower relative to β-lactoglobulin.
