Data transfer between storage apparatuses is reduced, and performance of data access of a storage system is improved. In a case where a processor of a first storage apparatus receives a write request from a host computer as a request for data access to a virtual volume and a cache memory of any of the storage apparatuses is not allocated to a virtual storage area in the virtual volume designated by the data access request, the processor of the first storage apparatus selects a second storage apparatus and a third storage apparatus among candidates satisfying a predetermined state condition among the storage apparatuses based on connection information indicating connection between the storage apparatuses through a communication line.