At the 1968 Olympic Games in Mexico City, he won the bronze medal in the bantamweight. In the semifinals, he defeated Valery Sokolov from the Soviet Union on points.
His professional career began in 1969 lasted only ten fights. His attempt to be Japanese bantamweight champion, failed in July 1970, Shintaro Uchiyama. After another defeat in September, Morioka retired from boxing.