In 1967, Ninomiya played for Mitsubishi Motors, he became a playing manager as Tomohiko Ikoma successor and managed until 1975. In 9 seasons, the club won the champions 2 times (1969 and 1973) and the 2nd place 4 times. The club also 1971 and 1973 Emperor's Cup. After Japan national team failed to qualify for 1976 Summer Olympics in April 1976, Ninomiya became a manager for Japan national team as Ken Naganuma successor. Ninomiya managed at 1978 World Cup qualification and 1978 Asian Games. He resigned after 1978 Asian Games.