This study examines the relationship between women directors and the cost of equity (COE). Investigating the French firm’s sample, we find a significant negative effect of women directors on the cost of equity. Our results also document that the effect of women directors on reducing the cost of equity is significant for firms that have a critical mass of at least four women directors. Using the difference-in-difference (DID) and propensity score matching (PSM) approach, we find that the relationship between female directors and lower equity costs is significant for the period following the Copé–Zimmermann gender quota law. The results show that women directors’ presence on corporate boards is also supported by economic reasons. The study provides implications in relation to the Copé–Zimmermann law in France.