A discrepancy between a management range of a user on a management computer, and a management range of the user in a storage, is detected with respect to a volume held in the storage. Storage management information of the management computer stores a correspondence between an identifier of a volume group, and an identifier of the user. When a plurality of volumes are designated as a managed object of the user, the management computer references the storage management information, and obtains, from the storage, an identifier of the volume group to which the plurality of designated volumes belong. Next, the management computer references the storage management information, and determines whether or not the obtained volume group is in the management range of the same user.