We develop a method to analyze the changes of communication structures in the local SNSs. As part of the steady growth of new network communication tools, the expansion of social network services (SNSs) such as Facebook and orcut is greatly affecting societies worldwide. On the other hand, the local SNS supports not only activities of the local society but is expected as a network infrastructure to support activities responding to disasters. We use time series analysis to visualize the communication networks among SNS users.