Morishima was born in Hiroshima on April 30, 1972. After graduating from high school, he joined Japan Soccer League club Yanmar Diesel (later Cerezo Osaka) in 1991. In 1992, Japan Soccer League was folded and the club joined new league Japan Football League. The club won the champions in 1994 and was promoted to J1 League. The club won the 2nd place at 2001 and 2003 Emperor's Cup. His opportunity to play decreased from 2007 and he retired end of 2008 season. He played 456 games and scored 140 goals for the club.
In 2000, Morishima played at 2000 Asian Cup. he played 5 matches and Japan won the champions. In 2001, he played at 2001 Confederations Cup. He played in all 5 matches and Japan won the 2nd place. At the 2002 World Cup he got three games as a substitute, scoring after two minutes in the game against Tunisia. He played 64 games and scored 12 goals for Japan until 2002.