Sunao Okamoto (?? ?, Okamoto Sunao, 1 September 1894 – 2 September 1955) was a Japanese male tennis player who represented Japan in the Davis Cup and the Olympic Games.
He competed in the singles and doubles events at the 1924 Summer Olympics.
In the singles event he had a bye in the first round and lost in the second round to Jan Koželuh.
With compatriot Takeichi Harada he won in the first round against Bjørn Thalbitzer and Einar Bache for the loss of just one game.
In the doubles he teamed up with Khoo Hooi-Hye, reaching the third round in which eventual champions Frank Hunter and Vincent Richards proved too strong.He became president of the Dai Ichi Trading company and later in life was an adviser to the finance ministry.