Upon graduation from Inha University in Incheon, Song made himself eligible for the 1996 KBO Draft and was selected in the second round by the Hanwha Eagles.
However, Song was hampered by arm injuries during the whole 2003 season, batting only .253 and hitting a career-low 9 home runs.
In the early 2000s (decade) Hyundai Group ran into financial problems, and eventually abandoned the Unicorns in 2007.
During a series of "fire sales" for the Unicorns' best players and franchises in the 2007 offseason, the Heroes kept attempting to trade Song for another big deal.
However, prior to the 2008 season, Song announced that he would stay with the Heroes, accepting the 60% salary cut offered by the team.