Provided is an agent for promoting growth of nonpathogenic oral indigenous bacteria, or an agent for improving oral bacterial flora, which comprises the dry powder of one or more mushrooms selected from the group consisting of Hericium erinaceus, Grifola frondosa, Lyophyllum shimeji, Hypsizygus marmoreus, Pleurotus ostreatus, Agaricus blazei, and Lentinula edodes, or an extract thereof, and which has an excellent growth-promoting effect on nonpathogenic oral indigenous bacteria and an excellent improving effect on oral bacterial flora, and which is effective in maintaining balanced indigenous bacterial flora. Also provided is a composition for oral use containing same.