Three-time Olympic men's 60-kg champion Tadahiro Nomura announced his retirement on Monday, saying his body has finally given in.
"I began to feel my physical limit," the 40-year-old Nomura said at a news conference. "I've done everything I can. I have no regrets."
Nomura, who said his surgically repaired knees and right shoulder had continued to worsen, will look to start a career in coaching.
He said the most memorable meet of his career was his last on Saturday at the All-Japan corporate individual championships, where he lost in the third round.
"A 40-year-old judoka got badly tossed but the crowd had it in them to offer huge applause and kind words. I couldn't have been happier," he said.
Renowned for his seoinage shoulder throw, Nomura won three consecutive Olympic gold medals from the 1996 Atlanta Games.
"I do feel a sense of sadness when I think about not competing again but equally, there's a refreshing feeling because I've given it my all," said Nomura, who did not compete at the last two Olympics.
"I've always thought about retirement, starting from my mid- to late-20s. From around April this year, I started thinking this could be my last year.
"I'll no longer be on center stage but I want it to be my job now to help bring up the young ones.
"(Judo) has given me something I can be proud of, a place to shine. I can say with pride that judo is my life."