東京都議会
While still a university student, Hagiuda began working as an aide to Ryuichi Kurosu, who was formerly a member of the Tokyo Metropolitan Assembly and mayor of Hachiōji. In 1991, at the age of 27, Hagiuda won a seat in the Hachiōji City Assembly, becoming the youngest candidate ever to do so. He then ran successfully for a seat in the Tokyo Metropolitan Assembly in 2002, serving part of one term. In 2004, he ran for a seat in the House of Representatives of Japan, which he won. Hagiuda then won re-election in the 2005 general election by a large margin. He lost his seat in the 2009 general election, then won in the 2012 general election and the 2014 general election.