IB Sports, the agency Kim left in April last year, failed to pay her 894 million won (793,960 dollars) earned from advertisement deals for Hyundai Motor and other companies, Kim's lawyer said on Monday.
"We filed the suit last November and the first court hearing was held on March 16 in Seoul," the lawyer Lee Sang-Hun told AFP.
"The sponsors continued to pay IB Sports for deals signed before April 2010 even after Kim left the agency, yet the firm did not give her share at all," he said.
Kim later set up her own agency, AT Sports.
"We're willing to return whatever she's due but we also need to get our share," Yonhap news agency quoted an IB Sports official as saying.
Kim, 20, who won gold at the 2010 Vancouver Winter Games, has been training in California with her new coach Peter Oppegard, with whom she teamed up in October after a split with her former coach, Canadian Brian Orser.
The figure skating champion dubbed "Queen Yu-Na" in her home country was listed by Forbes magazine last year as one of the world's highest-paid female athletes with annual earnings of 9.7 million dollars.
Kim was to compete at the World Figure Skating Championship in Tokyo scheduled for March 21 to 27 and flew to Seoul Sunday after the event was called off due to devastating earthquake and tsunami in Japan.