This study examines cross-national differences in gender earnings gaps in Japan, Korea, and Taiwan. It applies an extended model of the gender gap decomposition method, and tests four hypotheses, each of which focuses on a different possible source of the cross-national difference in gender gap. The decomposition results support the hypothesis emphasizing the cross-national difference in the distribution of males and females and the hypothesis emphasizing the difference in pay discrimination; the results do not support the hypothesis that the differences occur because of cross-national differences in females’ human capital. The main reasons for the larger gender earnings gaps in Japan and Korea than in Taiwan are higher segregation by gender and higher degrees of within-job pay discrimination in Japan and Korea. Despite similarities in welfare policies toward women, the difference in employment practices creates a substantial intra-regional variation in gender pay inequality in East Asia.