He played for several clubs, including Bellmare Hiratsuka, Avispa Fukuoka and Thespa Kusatsu.
Kojima started playing football when he was in the 5th grade and was converted to a goalkeeper at high school.
After graduating from Doshisha University in 1988, Kojima joined Fujita Industries (later Bellmare Hiratsuka) playing in the Japan Soccer League Division 1.
At the end of 1998, Bellmare released their main players including Kojima as well as Wagner Lopes, Hong Myung-bo, Kazuaki Tasaka and Yoshihiro Natsuka due to their financial problems.
In January 1995, Kojima was selected by the Japan national team for the 1995 King Fahd Cup, but did not play any game in the tournament.