To review published studies to assess the effects of supervisor training on the mental health of subordinate workers, and thereby develop an evidence-based guideline for supervisor training in promoting workers' mental health. Method: Seven studies that assessed the effect of supervisor training, whose outcomes included psychological stress responses of (subordinate) employees, were retrieved for assessment from PubMed, the Cochrane Library, MEDLINE, the Web of Science, and Ichushi-Web. An additional five studies were also reviewed for discussion on the content and types of training. Results: Providing supervisors with necessary skills and information on mental health, including relevant occupational stressors, has a favorable effect on workers' mental health, at least in the short term. The subject populations had a background of requiring mental health measures. The effect of the training varied depending on the participation rate of supervisors, suggesting that the overall effect on an organization may be limited without a certain extent of participation by supervisors. There is no evidence of a long-term (over 1 yr) effect of supervisor training, and the effect of education on the supervisors' knowledge and behavior tends to be lost after 6 mo.
Conclusion:The current evidence indicates that the following items should be taken into consideration for the development of a guideline for supervisor training: identification of high-priority populations requiring education, development of a strategy to improve the participation rate in education, inclusion of occupational stressors as well as basic information in workplace The primary prevention of mental health problems among workers has become a high-priority health care issue in many workplaces. Supervisor training is one of the most important measures to this end, because supervisors' attitudes and skills were found to be related to favorable working conditions and mental health among their subordinates 1) . Although the effect of supervisor training on workers' mental health has been suggested through research 2) , its utilization rate in workplaces in Japan is only 35% 3) . Reasons found for the lack of mental health measures in workplaces included "lack of knowledge on such measures" as well as lack of personnel who are in charge of the issue 3) . Therefore, the development of an evidence-based guideline and the preparation of instructions for training that can be carried out in workplaces may promote the training of supervisors. Although a trial of this process has begun 4) , to the best of my knowledge there have been no systematic reviews on the effect of supervisor training on workers' mental health. This study reviewed relevant effect assessment studies, for the purpose of developing an evidence-based guideline for supervisor training, as a primary measure to support workers' mental health.
MethodsThe studies published within the period of January 2000 to June 2009 were searched from the retrieval databases of PubMed, the Cochrane Library, MEDLINE, the ...