The storage controller of the present invention can efficiently execute recovery by using the storage contents of the primary volume and of the base volume as much as possible. The difference between the primary volume and the base volume is managed by using difference bitmaps that differ in the sections. At the time of recovery, the differences that occur after the restoration point and before the restoration point are managed in the respective bitmaps. The base volume can be used in the area updated only after the restoration point, and the primary volume can be used in the area updated only before the restoration point. In the areas that are updated before and after the restoration point, the data of the base volume is copied to the primary volume, and thereafter the journal data obtained up to the restoration point are written to the primary volume.