He graduated from Law Department of Kyoto University in 1921.
Hisao Shirakawa served as judge advocate of the army and later began practice of law (1925). Meantime served as mayor of Sumoto Town, Hyogo Prefecture, and became chairman of Awaji Chamber of Commerce & Industry.
He was elected to House of Representatives and parliamentary councilor of transportation. Held additional posts of president of Awajishima Unyu Kaisha (Awajishima Transportation Company) and Sumoto Gas Company and director of Awaji Kotsu Kaisha (Awaji Transportation Company) and Awaji Sangyo Kaisha (Awaji Industrial Company).