The purpose of this paper is to examine a relation between one's working circumstances and their working hours. The result from a regression analysis suggests that, with other things being equal, factors derived from severe working circumstances such as a lack of manpower, an excess work load and a tight work schedule due to a corporate restructuring make core male employees work longer hours. It is also found out that the longer hours they work, the less they are satisfied with their employers and their private life. The firms should enable employees to choose a more sustainable way of work from the point of view of CSR.