Proposed are a storage apparatus and hierarchical data management method for promoting the effective usage of memory apparatuses while suppressing maintenance-related costs and work. The storage apparatus comprises a plurality of memory apparatuses of a plurality of types, and a control unit for executing required data migration by monitoring an access frequency to each of the unit areas of the virtual volume and by controlling the corresponding memory apparatuses so that the storage area provided by the memory apparatus with a superior response performance is allocated to unit areas for which the access frequency is higher. The control unit controls the corresponding memory apparatuses so that when data is migrated from a first storage area, provided by a first memory apparatus which can be rewritten a limited number of times, to a second storage area provided by another second memory apparatus, the data is migrated to the second storage area without being deleted from the first storage area, manages updated parts of the data migrated from the first storage area to the second storage area after the data is migrated to the second storage area, and controls the corresponding memory apparatuses so that, when data which has been migrated from the first storage area to the second storage area is restored from the second storage area to the first storage area, the corresponding data still remaining in the first storage area is overwritten with the updated parts of the data which are updated after being migrated to the second storage area.