Shinojima was born in Nikko on January 21, 1910. In May 1930, when he was a Tokyo Imperial University student, he was selected the Japan national team for Far Eastern Championship Games in Tokyo and Japan won the championship. At this competition, on May 25, he debuted against Philippines. On May 29, he also played and scored a goal against Republic of China. He played 2 games and scored 1 goal for Japan in 1930.