The present invention provides a novel oxidized protein hydrolase activity enhancing agent. The oxidized protein hydrolase activity enhancing agent of the present invention contains at least one kind of plant extract obtained from a plant selected from the group consisting of water chestnut, stevia, rosemary, thyme, chrysanthemum, savory, mugwort, chestnut, spearmint, marjoram, peppermint, lemon balm, allspice, perilla, basil, and caraway.