Chang Won-jun (; born July 31, 1985) is a South Korean pitcher who played for the Doosan Bears of the KBO League.
He joined the Lotte Giants in the first draft in 2004, and played for the team between 2004 and 2014. On November 26, 2014, he declared it to be in the free agent market on the expiration of its preferential negotiation. After that, he signed an agreement with the Doosan Bears on November 29, 2014.
Chang represented South Korea at the 2017 World Baseball Classic.