A system and method of managing a social network are disclosed. The method includes the step of recording the IDs and corresponding personal information of users who have subscribed to a service via a network, in a user DB; the step of recording corresponding relationships between the users and relationship indices R, reflecting the degrees of trustworthiness of the users having the corresponding relationships, in a relationship information DB; and the path search step of evaluating one or more paths based on the relationship indices R of respective links constituting the paths and providing evaluation results to a first user so that the first user can select an optimal path from among the paths existing between the first user and a second user on the social network constructed with the users used as nodes and the corresponding relationships of the users used as the links.