The lightweight class was a judo event held as part of the Judo at the 1964 Summer Olympics programme. The weight class was the lightest contested, and allowed judokas of up to sixty-eight kilograms. The competition was held on Tuesday, October 20, 1964.
Twenty-five judokas from eighteen nations competed.
The twenty-five competitors were divided into seven pools of three and one pool of four. Each pool played a round-robin tournament, with the winner of the pool advancing to the quarterfinals. Pool D was the only one to require a playoff, which was won by Chang.
Pool A
Pool B
Pool C
Pool D
Pool E
Pool F
Stefano Gamba did not compete.
Pool G
Pool H
The remaining eight judokas competed in a single elimination bracket. Losers in the quarterfinals were placed 5-8 while both losers in the semifinals won bronze medals.