Sunao Tsuboi (?? ?, Tsuboi Sunao, May 5, 1925) is a Japanese anti-nuclear and anti-war activist and former teacher.
He is a hibakusha, a survivor of the atomic bombing of Hiroshima, and is the co-chair of Nihon Hidankyo, a Japan-wide organisation of atomic and hydrogen bomb sufferers.
In 2011 he was awarded the Kiyoshi Tanimoto peace prize.