Data is placed in tiered storage with a suitable granularity according to application characteristics. The storage apparatus comprises a controller for managing storage areas, provided by storage media of a plurality of types of varying performance, as pools, and for assigning the storage areas in page units to a virtual volume from any tiered storage among a plurality of types of tiered storage which the pool comprises in response to a data write request from the host computer, wherein, for specific data which is managed by the host computer, the controller specifies an area with a high referencing frequency among the specific data on the basis of organization information of the specific data, and moves this area to another of the tiered storage with a higher performance than an already assigned tiered storage.