Objectives: The aim of this study was to investigate the effect of a training program for managers on their management competencies and work engagement of their subordinate workers and to investigate the mediating effect of management competencies on the subordinate work environment. Methods: A training program, developed based on the UK Health and Safety Executive management competencies framework, was offered to managers in a finance company in Japan. Management competency was assessed at baseline and 1 month after the intervention. Work engagement was assessed at baseline and at a 1-year follow-up. Multilevel correlations between changes in components of management competency and changes in subordinate work engagement were analyzed. Results: Although 6 of 12 components of management competency increased significantly following the intervention, significant intervention effect on subordinate work engagement was not found. Among 12 components of management competency, the integrity of managers showed significant multilevel correlation with work engagement of their subordinates. Subgroup analyses revealed that this multilevel correlation increased when a manager and a subordinate differed in gender. Conclusions: The results of this study indicated that the training program developed in this study effectively improved the management competency of managers and that integrity of managers may facilitate work engagement of subordinate workers, especially when a manager and a subordinate are of different genders. Thus, a training program focused on improving the integrity of managers could enhance the work engagement of employees.