She served as Japan's first Minister of State for Gender Equality and Social Affairs from 2005 to 2006, and is currently a member of the House of Councillors representing Chiba Prefecture for the Liberal Democratic Party.

In addition, she has served as a lecturer at civil service training institutions and a commentator on foreign policy and international affairs for newspapers and television.

She also served the challenging post of President to the Conference on Disarmament from 18 August to 31 December 2003, and her efforts during this tenure were highly commended by Member States.

In addition to her duties as Ambassador Extraordinary and Plenipotentiary to the Conference on Disarmament, She was appointed Chairperson of the United Nations First Biennial Meeting of States on Small Arms and Light Weapons, held in New York in July 2003.

[3] Inoguchi declined to run in the 2009 general election after the LDP offered her a lower position on the proportional representation ballot.

She returned to the Diet following the 2010 House of Councillors election, in which she won a seat as an LDP candidate representing Chiba Prefecture.

During and after the 2005 election, she drew media attention for her collection of brightly-colored outfits, particularly a puffy blue dress that she wore to the Cabinet confirmation ceremony in the Imperial Palace.

[3] On the evening of November 27, 2024, a fire broke out inside the sixth-floor condominium unit in Bunkyo, Tokyo, where Inoguchi was living with her family.