This article summarizes the outcome of a comparative legal analysis conducted in seven countries (UK, Denmark, the Netherlands, France, Germany, US, and Japan) to obtain practical and theoretical insights into prevention and appropriate responses to the increasing issues around mental health in the workplace. The author worked closely with experts in a wide range of fields, including psychiatry, occupational medicine, business administration, human resources management, and sociology to characterize the issue and identify effective approaches from a legal perspective. Based on the findings, this article emphasizes the importance of ensuring procedural rationality and establishing a ‘circle of responsibility’ among the relevant parties.