Haruko Yoshikawa served in the House of Councillors as a member of the Japanese Communist Party from 1983-2007. She was a member of the Research Commission on the Constitution (憲法調査会) of the House of Councillors.

Yoshikawa's website explains her views regarding constitutional revision and includes articles regarding meetings, trips, and conventions she attended in which constitutional revision was discussed. She opposes allowing the Self-Defense Forces to engage in overseas military actions and changing Article 9.

She has supported former comfort women and victims of sexual violence, promoting gender equality. She has opposed the LDP and Nippon Kaigi, a nation-wide conservative group, changing Article 24, which determines “essential equality of the sexes''; she argues that the conservatives aim to revive the pre-war patriarchal system (2018 lecture).