Watanabe was born in Hiroshima on January 11, 1936. After graduating from Sotoku High School, he joined Yawata Steel (later "Nippon Steel") in 1954. In 1958, he left Yawata Steel and entered Rikkyo University. After graduating from Rikkyo University, he joined Yawata Steel again in 1962. In 1965, Yawata Steel joined new league Japan Soccer League. He retired in 1971. He played 79 games and scored 19 goals in the league. He was selected Best Eleven in 1968.