After retirement, Okuma became a coach at Tokyo Gas (later "FC Tokyo") from 1994. In 1994, he managed as caretaker in 1994 Emperor's Cup. In 1995, he became a manager and managed until 2001. In 2002, he became a manager Japan U-20 national team. He managed at the 2003 and 2005 World Youth Championship. In July 2006, he became a coach for Japan national team under manager Ivica Osim and Takeshi Okada. After 2010 World Cup, he resigned. In September 2010, he returned to FC Tokyo and managed until 2011. From 2014, he managed Omiya Ardija (2014) and Cerezo Osaka (2015-2016).