A storage system has an RMI interface for managing a storage. In starting an access, a WWW server distributes a storage manager program including an authentication function to a WWW browser of a manager. After a manager authentication by using a registered manager information file, an RMI management object dynamically creates an authentication key unique to the manager and an RMI interface having a limited function corresponding to the authentication key, and transmits the authentication key to a storage management program of the manager. An authenticated manager is allowed to imitatively use the RMI interface in accordance with the authentication key.