Soma was born in Shizuoka on July 19, 1971. After graduating from Waseda University, he joined Kashima Antlers in 1994. He played as left side-back and became one of the main player in glorious era of the club. In 1990s, the club won the champions in 1996, 1998 J1 League, 1997 J.League Cup and 1997 Emperor's Cup. He was also selected Best Eleven for 4 years in a row (1995-1998). In 2000, the club won all three major title in Japan; J1 League, J.League Cup and Emperor's Cup. However at Emperor's Cup in December 2000, he got hurt and he could not play about a year. Although he came back in the latter half of 2001, his opportunity to play decreased behind Augusto. In 2002, he moved to Tokyo Verdy on loan. He returned to Kashima Antlers in 2003 and moved to Kawasaki Frontale in 2004. At Kawasaki Frontale, he played as defensive midfielder and sweeper. He retired end of 2005 season.