This article discusses how women's movements in Japan function as political agents that change the political status quo. Japanese women's movements can be seen to comprise three groups: elite-initiated, feminist and non-feminist participatory. Despite differences in their outlook and attitudes, they share two common characteristics. First, their identities tend to be centred on motherhood. The language of motherhood has been a key idea behind Japanese women's mobilization. Second, their campaigns link women's demands with politics. Women's movements provide Japanese women, who are largely excluded from formal political processes, with an alternative channel for political participation. When they exercise practical influence on politics, they make effective use of channels both outside and inside formal political institutions, i.e. non-institutional and institutional channels. In the former case, the traditional style of Japan's policy-making makes political influence possible for the women. Use of institutional channels means electing female candidates to political office. Women's movement organizations provide those candidates with support for their election campaigns. It is clear that women's political involvement at the grassroots level has contributed not only to improving women's social conditions but also to developing a more democratic political system in Japan.