After World War II, Kawamoto played at 1954 World Cup qualification and 1954 Asian Games. On May 3, 1954, he made history by becoming the oldest player to play for Japan national team at the age of 40 years and 106 days. He played 9 games and scored 4 goals for Japan until 1954. He was also a member of Japan as player and assistant coach for 1956 Summer Olympics, but he did not play in the match.