Ballad of Seo Dong (Hangul: 서동요; hanja: 薯童謠; RR: Seodong-yo) is a South Korean television series starring Jo Hyun-jae, Lee Bo-young and Ryu Jin. It aired on SBS from September 5, 2005 to March 21, 2006 on Mondays and Tuesdays at 21:55 for 55 episodes.The period drama is based on Seodong-yo, said to be one of Korea's oldest folk songs and its first hyangga.