In 1959, when Naganuma was player, he became a manager for Furukawa Electric. In 1960, he led the club won to 1960 Emperor's Cup champions. This was the first Emperor's Cup champions as a works team. In 1962, when he was 32 years old, he named a manager for the Japan national team as Hidetoki Takahashi successor. He managed Japan with assistant coach Shunichiro Okano at 1964 Summer Olympics in Tokyo and 1968 Summer Olympics in Mexico City. At 1968 Summer Olympics, Japan won Bronze Medal. This is the first time an Asian team won a medal at Olympics. In 2018, this team was selected Japan Football Hall of Fame. He also managed at 1966 Asian Games. In 1969, he resigned after 1970 World Cup qualification and Okano was promoted to new manager.