Later than in the West, Compact City Policy recently has been discussed in Japan for an aging society as a city policy that is environmentally friendly, convenient especially to the aged with less access to private transportation and economical to administrative entities. However, less discussion is held on risks of introducing a Compact City Policy on life with drastic changes social environment (ex. social ties). Moreover, discussions in Japan should be unique inasmuch as the Japanese lifestyle differs from that of the West. As the first step to identify risks in Japan, this study aimed to predict impacts of a Compact City Policy on social ties and satisfaction with friends according to urbanism patterns with open large-scale volume data (mainly, JGSS-2006[Japanese General Social Surveys]). To analyze the impacts, we divided social ties into three categories: participation in community activities, belonging to organizations and frequency of meals with friends. Subsequently, we clustered the ‘City Population Scale' identified by prefecture and the population scales of cities into three groups according to ‘Urbanism Pattern Indices', namely proximity between house and workplace, accumulation of urban function of commerce and medical services, and transportation less dependent on private cars, to determine the characteristics of a compact city. The preliminary study revealed that ‘City Population Scale' divided by the above indices shows common geographical features in each cluster. In the main analysis, this study not only found different impacts of urbanism patterns on social ties and the satisfaction with friends, but different impacts of social ties on the satisfaction with friends according to urbanism patterns. These impacts varied according to personal attributions. This study suggests need for a risk mitigation policy after the introduction of the Compact City Policy for each cluster. In conclusion, the study suggests risk management policy is necessary for the social environment after introduction of the Compact City Policy, and finally proposes that large-scale volume data contributes to a more detailed tailor-made analysis as shown by this study. JEL Classification: I39, P41, R58