After the economic recession of the 1990s, mental health issues such as “karoshi (worked to death)” emerged, highlighting the distinctive mental characteristics of Japanese society. As part of diverse human resource management, there is a need for working environments where employees can work healthily, even if they have mental or physical health problems. This study clarified the trajectories of how people who experience sick leave either return to work or change jobs. In particular, it paid attention to the pathway from taking sick leave to either returning to work or leaving work and compares the differences in the working environment before and after sick leave. First, this study found that the periods of leave and unemployment differed significantly between those who returned to work or changed jobs after sick leave and those who remained unemployed or continued on leave after sick leave. The period of leave for the latter tended to be longer than the average period of injury receipt and illness allowance. Given the differences in the periods of leave and unemployment for different health reasons, the systems of recurrent sick leave and social security should be adjusted to suit circumstances based on particular injuries or illnesses. Second, the study found that the working environment after leave was often better for those who left and found a new job after sick leave than for those who returned to work after sick leave. Finally, it was found that a good working environment makes it feasible for people to once again engage in work after having left a previous job after leave.