Ouchi Mochitoyo (died autumn 1187) was the daimyo of the Ouchi clan and lord of Hoki Province from 1187, succeeding Ouchi Koresato. He was an enemy of the Kamakura Minamoto as an ally of the Yashima Taira. Minamoto Mitsunao and the Minamoto invaded his lands in autumn 1187 and he died in the Siege of Kurayoshi Castle, with the Minamoto capturing Hoki from the Ouchi, and they made the Hasebe clan their vassals.