In the studies of organizational stress conducted in the U. S. and western Europian countries, human relations at work place has been treated as one of the important environmental stressors. In Japanese work organizations, however, human relations should be regarded as a factor which moderates (buffers) the negative effects of organizational stress. That is why, Japanese workers seem to cope with stress effectively on the basis of good relationships at work. The present study was designed to examine the stress buffering effects of human relations in organizational stress-mental health relationships. Survey data obtained from 334 Japanese white-collar workers of a large supermarket chain and a bank were analyzed by using the moderated multiple regression technique and the subgroup method. The results suggested the buffering effects of human relations in organizational stress (workload, role ambiguity, and role conflict)-mental health (somatization, anxiety, and particularly depression) relationship. Arguments were advanced for the future application of the present findings to the social support study in work settings.