From 1995 he served as governor of Hokkaidō for two terms totalling 8 years.

Tatsuya Hori originally comes from Tomakishi, Karafuto (Vakhrushev, Sakhalin).

Under Governor Takahiro Yokomichi, he was assistant director of the Public Works Department, room monitor for the governor, and municipal utility administrator.

In 1997, after the bankruptcy of the Hokkaidō Colonization Bank, he declared a state of emergency and called for a restructuring of Hokkaidō, but public utilities expenses deteriorated for which he will always be remembered.

After stepping down as governor, he assumed the office of board chairman of Sapporo University in August 2008.