He graduated from the law school of Tokyo Imperial University in 1905 and received a posting to the Ministry of Communications.

[citation needed] Tanabe was drawn into politics over the debate for constitutional revision at the time of the Kiyoura administration, and denounced the privileged position of the bureaucracy.

[citation needed] However, conservative Minister of Justice and President of the House of Peers, Kiichirō Hiranuma thought very highly of Tanabe, and invited him to accept a position on the board of his Kokuhonsha, a nationalist political group founded in 1924.

In 1927, he was appointed Governor of Osaka by Home Minister Suzuki Kisaburō, another Hiranuma protégé and Kokuhonsha member.

He supported the viewpoint of the Kwantung Army that private management of industries was more realistic than a completely state-controlled economy.