Haruo Oka, real name Tatsuo Sasaki, was a Japanese ryūkōka singer.
He studied music as an enka-shi or a street musician. At that time, he was encouraged by Taro Shoji in Ginza. He signed with King Records in 1938. He debuted with song "Kokkyō no Haru" in 1939. He married Kiyoko Okuda in 1940. In 1944, during the Pacific War, he was dispatched to Ambon Island, but soon returned due to sickness.
After the war, his popularity grew, and he starred in Akogare no Hawaii kōro with Hibari Misora. However, he never performed at the Kohaku Uta Gassen partly because he attached importance to live performances.