Eldest son of Ryusaburo Mizuno, a samurai of the Akita clan. He graduated from the Imperial University of Tokyo in 1892. He served as sanjikan (councillor) of the Home Ministry, secretary to the Home Minister, director general of the Shrine Affairs Bureau, director general of the Engineering Bureau and director general of Local Affairs Bureau of the Home Ministry. He was selected as a member of the House of Peers by Imperial command in 1912. He was appointed the Vice Home Minister in 1913, the Home Minister in the Terauchi Cabinet in 1918, in the Tomosaburo Kato Cabinet in 1922, and in the Kiyoura Cabinet in 1924, as well as the Education Minister in the Giichi Tanaka Cabinet in 1927. He also served as the Inspector General of the Political Affairs under Saito, Governor-General of Korea in 1919. He assumed the post of the president of Kyochokai in 1940 and the vice-president and the president of Dai Nihon Koa Domei in 1942 and 1943 respectively. After the war, he was suspected of being a class-A war criminal. He was, however, deleted from the list and purged from public office.Jur. d..