The present invention provides a high-performance storage access environment to a user who moves around a wide area, while increasing the fault resistance of the system. A plurality of network storages (volumes) is assigned to the user. Then, at the occasion of logging in to a volume by the user, the volume that can be accessed with high performance from a position he made access is located. Addresses at a computer with which user makes access are associated with addresses of the volumes provided by a storage device in advance in an assigned volume management table so as to increase access performance. Then, a management server performs control so that the address of the volume associated with the user access position is returned as a response, at the time of logging in.