Objectives: Although incivility is a common interpersonal mistreatment and associated with poor mental health, there are few studies about it in Asian countries. The aim of this study was to develop the Japanese version of the modified Work Incivility Scale ( JMWIS), investigate its reliability and validity, and reveal the prevalence of incivility among Japanese employees in comparison with data on Canadian employees. Methods: A total of 2,191 Japanese and 1,071 Canadian employees were surveyed, using either the J-MWIS or MWIS. Japanese employees additionally answered questions on civility, worksite social support, workplace bullying, psychological distress, intention to leave, and work engagement to investigate construct validity. Results: At least one form of workplace incivility was experienced by both Japanese ( 52.3% ) and Canadian (86.0%) employees in the previous month. Internal consistency reliability of the J-MWIS was acceptable (a= 0.71-0.81), and correlation analyses also confirmed its construct validity as expected. Workplace incivility was associated with lower workgroup civility, lower supervisor and coworker support, higher workplace bullying, higher psychological distress, higher intention to leave, and lower work engagement. Confirmatory factor analyses showed that the original three-factor model (supervisor incivility, coworker incivility, and instigated incivility) fitted moderately in both Japan and Canada data, though the privacy/overfamiliarity factor was additionally extracted from exploratory factor analysis for the J-MWIS. Conclusions: The results of this study suggested that the JMWIS has moderate internal consistency reliability and good construct validity.