In this paper, we examine how job assignments affect gender pay gap and the promotion rate of female workers using personnel records from a large Japanese manufacturing firm, where newly-hired male and female workers are systematically assigned to different workplaces (“gender job segregation”). According to our gender pay gap analysis, we find that controlling for workplace heterogeneity leads to a larger, rather than smaller, gender pay gap, implying that female workers are sorted into workplaces where they have better prospects for promotion and wages are relatively higher. In further analyzing what determines the promotion of female workers, we find a striking difference by education level. For college and graduate school-educated women, both personal factors (university ranking, graduate degree, and the experience of transfers) and workplace factors (R&D department and the incidence of female managers) raise the promotion rate. Especially, the latter is more important. We confirm that female managers concentrate in specific workplaces, and that new managers are more likely to be female in those workplaces than in others.
