Some difficulties in dealing with the mental health of large company employees in their 40s and 50s are discussed based on the authors' experiences as infirmary psychiatrists over the last decade. Some characteristics of Japanese enterprise are introduced and explained, such as "Tanshin-Funin," "Madogiwazoku" and "Shukko," which are intimately related to the management system of modern Japanese companies. The most prevalent psychiatric disorders among company employees are briefly discussed. They are usually diligent and hard-working middle management employees at least until the disorder becomes manifest. Form the socio-psychiatric viewpoint, it is assumed to be of increasing importance to deal with such a large cohort of individuals working in large companies as one of the significant objects of contemporary hygienic activities.