The second of three siblings, Song was raised in the rural outskirts of Daejeon. He competed in short track speed skating and represented his home city of Daejeon at national level (he would go on to portray a national speed skater in the TV series Triple). An injury forced him to give up the sport during his first year of high school. He excelled in his studies all through high school and scored 380 points out of 400 on his national college entrance test, gaining admission to Sungkyunkwan University. While in Seoul preparing for the entrance test, he was scouted on the subway by an agent but did not immediately enter the entertainment industry as he was still ambivalent about his career path, and because his father had initially been against him becoming an actor. He continued to study part-time after deciding to enter the entertainment industry full-time during his third year of university, eventually graduating with a degree in Business Administration (minor in broadcasting) in 2012.