The supply and demand theory provides an appropriate analytical perspective on the serious imbalance in the gender ratio of Japanese politicians. From the supply perspective，women are less likely to work in politics-related jobs before entering political arena and consequently lack political resources compared to male politicians. Hence，there are not sufficient female citizens who are eligible to run for political office. From the demand side，Japanese conservative parties are relatively negative about improving the status quo of gender equality；meanwhile，constituencies that are less economically developed or dominated by conservative parties are likely to be biased against female politicians，both of which are underlying barriers to women’s equal participation in politics. Therefore，if major parties such as the Liberal Democratic Party （LDP） strengthen their “demand” for female politicians and nominate more female candidates for national elections，the proportion of female members of parliament will significantly increase，thus ensuring progress towards gender equality in Japanese politics.