A scale for measuring gender harassment of women by men, as well as by other women at workplaces in Japan was developed. Firstly, items related to gender harassment were generated through semi-structured interviews. Then, a questionnaire containing these items was administered to a sample of working Japanese men and women (N = 354; 132 female, 222 male). Factor analysis was conducted on the responses to the questionnaire. The result indicated that gender harassment had the same two-factor structure in both sexes. Then, the relationship between gender harassment and sexual harassment of workplace incivilities, such as general forms of mistreatment, was analyzed in the sample of men. The results suggested that gender harassment was linked to sexual harassment; however, the two concepts are different, at least in Japan.