After graduating from Tokyo University (1903) Okada Tadahiko entered government service through Ministry of Home Affairs and has seen service as Governor of Saitama, Nagano and, Kumamoto prefectures, chief of Police Force and Vice-Governor of Tokyo. In between made several official trips to Europe, America and Asian countries.
Okada Tadahiko entering politics as a member of Liberal Party was elected to House of Representatives eight times, and was speaker of the Lower House and Minister of Welfare in the Suzuki Cabinet (1945).
Retired from politics after the end of the war and was president of Seto Inland Sea Sight-Seeing Railway Company.
Among his works are "One Glance at South China" and "Western Nations in a Whirlwind."