This invention provides a storage system to store data used by computers. A storage system coupled to a computer and a management apparatus, includes storage devices accessed by the computer and a control unit that controls the storage devices, in which the control unit performs the following operations: setting, in the storage devices, a first virtual device including a first logical device; setting a second virtual device which including a second logical device, which is a virtual volume accessed by the computer; allocating an address of the first logical device to the second logical device; and changing the allocation to change storage areas of the virtual volume.