It is generally accepted amongst demographers that a declining fertility rate has negative economic consequences, namely in the guise of a slowdown in economic growth. Declining fertility has, therefore, been seen as a major problem in Japan and the EU for the last 20 years. Over the past two decades, demographers and social scientists have discussed intensely the causal connection between gender equality and female fertility, to the extent that during the past 10 years, gender equality has become the cornerstone of the EU and, to a degree, Japanese public policy aiming to re-optimise fertility rates. This article scrutinises the different ways in which gender equality is erected by demographic and social scientists in Japan and the EU as a technology of governance with the aim of re-exerting control over sexual reproduction. I argue that in the EU, scientists engage directly and endeavour to develop demographic theory based on European case studies, whereas Japanese gender equality policy is developed mainly by measuring the successes of European gender equality policy and considering the results it might yield in Japan. In both cases, however, gender equality is taken up as a tool for the governance of fertility.