In 1986 he was elected to the House of Representatives in the Diet (national legislature) for the first time.

He served six consecutive terms as a member for Nagano No.4 district (1986–1996), Nagano No.2 district (1996–2003) and the national proportional representation block (2003–2005).

Whilst in the Diet he served in various ministerial roles, including as Minister of State for Food Safety, Minister of State for Disaster Management and Chairman of the National Public Safety Commission.

In July 2005 he voted against the government's postal reform legislation and subsequently lost the support of the Liberal Democratic Party.

In the following year he was elected governor of Nagano Prefecture and served one term.