We reviewed recent concepts of social support networks and results of epidemiological studies on the relationship between the social relationships and health status of the elderly. Recent scientific researches have established strong empirical evidences for a causal impact of social relationship on the health status of the elderly. We showed our community-based longitudinal comparative epidemiological study data. From 1991, in Hokkaido prefecture, the health and the social relationship in the elderly living in three areas included a large city “Sapporo”, an ex-coal-mining town, and a rural area “Takasu”, were studied. Lumbar pain and arthritis were main symptoms that the elderly living in the rural town complained more frequently than in other areas. Number of persons with declined activities of daily living (ADL) or with dementia, who might need serious care and support from others, was not significantly different in three cohorts. However, availability of social supports and social participations of the elderly in the rural area was the best and highest among the three areas. From our prospective cohort data in men living in the rural area, Cox proportional hazard analysis showed emotional supports and social participations had protective effects to mortality after adjusting age, health behaviors and the subjective and objective health status. Such effects were not found in women. These findings suggests that the community care system in each town should pay attention to social relationship, especially participation of the elderly themselves. In addition, we discussed some future issues on the community health-care and welfare systems for the elderly and related policies in Japan.