A specific client computer acquires content that has been stored in a content server. To accomplish this, the ID of the client computer is registered with the content server. The IP address, etc., of the content server is encrypted to obtain a check code and the check code is transmitted to the client computer and to a center server. The check code, etc., is transmitted from the client computer to the center server. The center server decrypts the check code transmitted from the client computer and the check code transmitted from the content server. The IP address, etc., of the content server is obtained by the decryption. If the IP address, etc., obtained from the check code transmitted from the client computer and the IP address obtained from the check code transmitted from the content server agree, the center server decides that the client computer is an authorized computer and transmits the IP address of the content server to the client computer. The authorized client computer thus ascertains the IP address of the content server and can obtain content from the content server.