Disclosed is a use of a whey protein hydrolysate having (1) a molecular weight distribution that is within a range of 10 kDa or less and has a main peak of 200 Da to 3 kDa, (2) an average peptide length (APL) of 2 to 8, (3) a free amino acid content of 20% or less, (4) a branched-chain amino acid content of 20% or more, and (5) an antigenicity equal to or less than 1/100,000th of that of &bgr；-lactoglobulin in the manufacture of a medicament for the prevention of muscular atrophy.
