The possible associations of intragroup and intergroup conflict at work with psychological distress and work engagement were investigated in a cross-sectional study in a manufacturing factory in Japan. A self-administered questionnaire was sent to all employees, and 255 responses were returned (a response rate of 84%). Data from 247 workers (187 males and 60 females) with no missing values were analyzed. Intragroup and intergroup conflict at work, psychological distress, and work engagement were measured by the NIOSH-GJSQ, K6, and Utrecht Work Engagement Scale (UWES-9), respectively. An ANCOVA was conducted to compare K6 and UWES-9 scores among the tertiles on intragroup conflict or intergroup conflict scores, adjusting for demographic and occupational variables as well as worksite social support, separately for males and females. Intragroup conflict was associated with greater psychological distress for males (p for trend=0.009). Intergroup conflict was marginally significantly associated with psychological distress for both males and females (p for trend=0.050 and 0.051, respectively). Contrary to expectation, intergroup conflict was significantly associated with greater work engagement for females (p for trend=0.024). For males, intragroup and intergroup conflict at work may increase psychological distress; for females, intergroup conflict may increase both psychological distress and work engagement.