Choi Yun-kyum made the decision following Gangwon's 2-0 loss to Jeju United in the top-flight K League Classic on Sunday, the club said.
Gangwon FC have lost four of their last five matches, slipping from third to sixth in the 12-team league.
With 37 points on 10 wins, nine losses and seven draws with 12 matches remaining, Gangwon FC are nine points back of Suwon Samsung Bluewings in third place, the last qualification spot for next year's Asian Football Confederation Champions League.
|In this file photo taken on Aug. 2, 2017, Choi Yun-kyum, then head coach of Gangwon FC, awaits the start of his club`s K League Classic match against FC Seoul at Seoul World Cup Stadium. Choi resigned from his post on Aug. 14, 2017. (Yonhap)|
Gangwon FC were among the busiest teams in the last offseason, as they acquired a handful of proven veterans to make a run at the K League title and an AFC Champions League berth.
Choi said he felt it was time for a change at the club.
"We still have a chance to qualify for the AFC Champions League, and I made this difficult decision because the club needed a change," Choi said. "I hope Gangwon FC can make it to the AFC Champions League in a new atmosphere."
Choi, who took over Gangwon in 2015, leaves with a record of 44 wins, 36 losses and 30 draws. He is the longest-tenured and the winningest head coach in the club history.
Senior assistant Park Hyo-jin will be the interim head coach for the rest of the season. (Yonhap)