A receiver receives from a client, a participation request indicating that a delivery of a content is desired. An affiliated group-determining unit determines of which group corresponding to the attribute content the attribute of the user, included in the participation request is affiliated. When the other client corresponds to the same desired content and the same affiliated group as that of the participation request source client, and when the other client is already registered in a client database (DB), an access point-deciding unit decides the registered client as a access point of the participation request source client. When the other client is not registered in the client DB, the access point-deciding unit decides a delivering server as the access point of the participation request source client.