This study compares regular and involuntary non-regular workers who hold white-collar jobs regarding the relation between their job satisfaction and mental health. In determining job satisfaction,particular attention was given to the support provided by supervisors and co-workers. Data were collected from 441 regular workers and 311 involuntary non-regular workers using a web-based questionnaire survey and then analyzed. First,five subscales regarding job satisfaction were created using factor analysis: specifically,the individual contributions and activities,supervisors’ active listening attitude,amount of discretion allowed in their jobs,evaluation by others and treatment,and supervisors’ capabilities and ability to manage. In addition,a scale for the number of supportive coworkers and an index for determining mental health conditions were created. A t-test showed that compared to involuntary non-regular workers,regular workers had higher satisfaction regarding individual contributions and activities,the amount of discretion allowed in their jobs,and evaluation by others and treatment. However,they had lower satisfaction regarding the supervisors’ active listening attitude. Following this,using running multiple regression analysis,it was found that the mental health condition of regular workers was impacted by age and the extent to which they were satisfied with their supervisors’ active listening attitude. For the involuntary non-regular workers,this impact came from the amount of satisfaction associated with individual contributions and activities,the supervisors’ active listening attitude,as well as the number of supportive co-workers and age. Thus,these findings indicate that the supervisors’ positive and active listening attitude towards their subordinates who approach them for consultation is an ideal way to counter negative mental health conditions for both regular and involuntary non-regular workers.