In June 1956, when Yaegashi was a Waseda University student, he was selected Japan national team for 1956 Summer Olympics qualification. At this qualification, on June 3, he debuted against South Korea. In November, he played at 1956 Summer Olympics in Melbourne. He also played at 1964 Summer Olympics in Tokyo and 1968 Summer Olympics in Mexico City. At 1968 Olympics, he played as a captain in first match against Nigeria, he was replaced for injury in the 78minuts. This match is his last match for Japan. After the match, Although he could not play, he supported Japan team and Japan won bronze medal. In 2018, this team was selected Japan Football Hall of Fame. He also played at 1958, 1962 and 1966 Asian Games. He played 45 games and scored 11 goals for Japan until 1968.