Protease hydrolyses of an Okara protein yielded antioxidative activity against the peroxidation of linoleic acid in an aqueous system at pH 7.0. Four antioxidative peptides were isolated from the hydrolysate prepared with Protease N by size exclusion chromatography and reversed-phase HPLC. The peptides were composed of two and three amino acid residues, including aromatic amino acid at the C terminal end. Their amino acid sequences were determined to be Ala-Tyr, Gly-Tyr-Tyr, Ala-Asp-Phe, and Ser-Asp-Phe, respectively. The antioxidative activity of Gly-Tyr-Tyr is nearly equal to that of carnosine.