Masushi Ōuchi (大内 仁, Ōuchi Masushi, September 28, 1943 – June 6, 2011) was a Japanese weightlifter who won a bronze medal at the 1964 Summer Olympics and a silver medal at the 1968 Summer Olympics. He won two gold medals at the Asian Games in 1966 and 1970. He further became the world champion in the light-heavyweight category in 1969. In 1965–1969 Ouchi set eight world records – six in the snatch and two in the total. Later in life, Ouchi won four world titles in the masters category.