This study examined whether the presence of female executives serves as a determinant in explaining the effects of income smoothing on firm value and the value relevance of accounting information. According to prior research, managers engage in income smoothing for two purposes: first, to provide meaningful private information to investors by reducing earnings volatility, thereby enhancing firm value; and second, to increase managers' own opportunistic utility. This study focused on the first purpose—income smoothing aimed at enhancing firm value—and investigated whether income smoothing positively affects firm value and the value relevance of accounting information when female executives are present in the firm. In other words, based on prior research suggesting that the presence of female executives brings diverse perspectives to the firm and that female executives tend to be more ethical and trustworthy than their male counterparts, we predicted that the effect of income smoothing on firm value and the value relevance of accounting information would vary depending on whether the firm has female executives. Since the disclosure of executives' gender became mandatory from November 2013, we calculated the presence and proportion of female executives using data from 2014 onward and conducted empirical analyses on 4,000 firm-year observations from 2014 to 2016. The results can be summarized as follows. First, when female executives are present in a firm and when the proportion of female executives is higher, income smoothing was found to enhance firm value. This can be interpreted as indicating that firms with greater gender diversity in their executive composition engage in income smoothing for the purpose of enhancing firm value through reduced earnings volatility, rather than for managers' individual opportunistic motives. Second, firms with female executives exhibited higher value relevance of accounting information compared to firms without female executives, and furthermore, in firms with female executives, the value relevance of accounting information increased as the degree of income smoothing increased. This can be interpreted as indicating that when female executives are present, income smoothing is conducted for the purpose of providing private information to investors rather than for opportunistic incentives. This study is significant in demonstrating that the presence of female executives serves as a determinant in whether income smoothing brings positive effects to the firm.