Storage system and data management method to reduce the load on a virtualization apparatus by executing backup processing or restoration processing within one apparatus in which an externally connected storage apparatus and a tape library apparatus are installed. The storage system includes a virtualization apparatus and an external storage apparatus; the virtualization apparatus having: an actual volume for storing data sent from a host apparatus, formed in a storage area provided by a physical disk; and a virtual volume paired with the actual volume, for storing replicated data for the data, and the external storage apparatus having: a logical volume that functions as an actual storage area for the virtual volume; and a tape associated with the logical volume, for storing the replicated data, wherein the external storage apparatus has a copy unit for copying the replicated data stored in the logical volume to the tape.