The purpose of this paper is to grasp what kinds of factors induce depression, which is an antecedent factor in overwork-induced suicide. To attain this purpose, an online questionnaire survey was conducted targeting middle management personnel. The research subjects were the effects of job stressors, working conditions, personal situations, and the factors other than business on depression.

The results of the questionnaire survey are as follows: Firstly, role conflict, role ambiguity, and quantitative workload influenced depression strongly. Secondly, the necessity of cooperation and career history influenced depression slightly. Thirdly, the ratio of personal income to household income influenced depression slightly. Fourthly, the factors regarding melancholic type personality and organizational commitment did not influence depression. Long-time work, which is a major concept in the research into overwork-induced suicide, did not influence depression.

As a result of the questionnaire survey, the following 2 facts were clarified. Firstly, many factors that have been pointed out in the previous researches into overwork-induced suicide have not been studied empirically. Secondly, there is a high possibility that we will be able to predict overwork-induced suicide by many factors that have been pointed out in the study of stress. Therefore, it is necessary to utilize the results of the study of stress, in order to advance the research into overwork-induced suicide. This would diversify the methods for seeking how to grasp the causes of overwork-induced suicide.

In addition, in order to develop methods for preventing overwork-induced suicide, it is necessary to discuss the following items.

Firstly, in order to prevent overwork-induced suicide, it is necessary to focus on job contents and roles at workplaces. Secondly, it is necessary to further discuss the factors of role conflict, role ambiguity, and quantitative workload, to identify the mental and work-related factors in overwork-induced suicide. Thirdly, it is essential to discuss what kinds of events occur between the onset of depression and committing suicide and how much these events increase stress.