Pak won the Pyongyang Marathon on 13 April 2014 with a personal best of 2:12:26. The winning time was an improvement of more than a minute from his previous personal best which earned him the fifth place in the same race in 2013. In 2015, he came second in the 15th Asian Marathon Championship in Hong Kong with a season's best of 2:16:09. He took part in the marathon at the 2015 World Championships in Beijing the same year and placed 11th with a time of 2:15:44, a new season's best.