Lee was born in 1989 as the 25th generation of the Injegong branch in the HansanLee clan. Lee's father, Lee Do-won is a department manager at the Kyunghyang Sinmun newspaper. Lee's family members are devoted Buddhists. Lee started skating as a hobby in 2002 when he was in fourth grade at Seongok Elementary School. The school in the neighborhood of Wolgye-dong, Nowon-gu, Seoul is located next to the ice rink at Kwangwoon University. Lee's older sister, Lee Hwa-yeong was a figure skater regarded as a rising rookie, who won an elementary competition at the Korean National Sports Festival when she was in 6th grade. During the time, Lee's coach recommended Lee to be a professional skater. As Lee's school established a skating team, Lee joined it. Two years later, he switched from long track speed skating to short track speed skating. On the other hand, Lee's parents had financial difficulties in supporting their children's dream. They had to spend over 2,000,000 won per month for the fees of skating lessons, purchasing skating tools and renting exercising locations. Although Lee's parents worked together, spent all savings and even sold paddy fields in a countryside to support their children, that was not enough to cover all. They finally had to loan mortgages on their house where the family was living. However, Lee's sister eventually gave up due to the financial situation and tried to seek her future in other sport genres that cost less money for training such as inline skating and wakeboarding. The fact that his sister had to drop her dream has stimulated Lee Jung-Su to focus on the skating training. Lee graduated from Gwangmun High School, and is, as of 2010, attending Dankook University. Lee has been handed a 3-year ban along with his teammate Kwak Yoon-Gy for controversial foulplay. Lee had written a note stating that he was not fit to compete in the World Championships 2010 Sofia, because of an injury. This turned out to be not true, and Lee admitted that his coach forced him to pull out so that he could give teammate Kwak Yoon-Gy a chance to win a medal. Kwak Yoon-Gy went on to win Gold in the 1500m.
