The Japan Endocrine Society (JES) has the largest ratio of female membership among societies associated with Internal Medicine in Japan; half of female members are in their 20s or 30s at present. In 2009, JES organized the "JES-We-Can" committee to promote women's career development. To evaluate the effectiveness of JES-We-Can, we investigated the gender balance of various activities at JES in fiscal 2009 and 2017. Significant gender-differences were not observed in the acquisition rate of board-certified endocrinologists (BCEs) aged <40 y in 2009 and 2017. However, the acquisition rate of BCEs among women aged ≥40 y was significantly lower than men in 2009. In 2017, the gender-difference among BCEs in this group (currently aged ≥50 y) has considerably improved, but is not resolved. The acquisition rate of certificated endocrine educators (CEEs) among women was still significantly lower than men at all ages in 2017. Since the ratio of women oral speakers or poster presenters at annual academic meetings have grown to equal or surpass the membership ratio, female members make efficient contributions to JES. The numbers of women chairpersons, symposiasts, lecturers and invited speakers have increased, but remain limited. JES-We-Can was found to be effective in reducing the gender gap in academic activities at JES, but JES-We-Can should support women more intensely to raise the rate of CEEs among all ages and BCEs currently over 50 y, and to promote more women into higher positions in JES in the future. These actions are expected to introduce new and diverse perspectives into academia.