Studying in New Zealand at the time, a role in the popular MBC sitcom Nonstop 4 brought him back to South Korea.
Seeing his potential, the agent advised Jang's parents to allow him to try a career in modeling.
In junior high school, Jang went to school in New Zealand, where he attended Nelson College in 2003, to learn English and Japanese.
In 2006, Jang debuted in the big screen for the Japanese horror film One Missed Call: Final where he played the role of a deaf boy.
He next played the first love of famous gisaeng Hwang Jini (played by Ha Ji-won) in the period drama Hwang Jini.
In 2008, Jang would go on to act in two more music-inspired projects with the film Do Re Mi Fa So La Ti Do and the MBC drama Beethoven Virus opposite Kim Myung-min, in which he played a trumpet player in an orchestra.