This storage apparatus has a controller for controlling, upon receiving a read request regarding data of the snapshot image of a prescribed generation from the host system, the reading of the data of the operational volume or the differential data of the pool volume as data of a snapshot image of a corresponding generation based on the generation of the snapshot and the storage destination of data of the snapshot image managed by the snapshot management unit; wherein the controller performs control so as to store the data stored in the operational volume as replication data in the pool volume when reading the data from the operational volume, and read the replication data stored in the pool volume when rereading the data stored in the operational volume.