He was the number two draft choice of the Hanshin Tigers in 1998. After a couple of years in the Hanshin minor league system, Igawa entered the starting rotation in 2001. In his first full season as a starter, Igawa went 9-13 for the last-placed Tigers, but finished with a Central League second-best 2.67 ERA, behind only Chunichi's Shigeki Noguchi.