A storage system includes: a storage device configured to copy data to another storage device, the storage device includes: a first storage region configured to store the data; a first receiving unit configured to receive a first instruction from a higher level device; a transferring unit configured to transfer the instruction from the higher level device to the another storage device; and a first storage region releasing unit configured to release the first storage region, wherein, when the first instruction is a releasing instruction instructing to release the first storage region, the transferring unit transfers the releasing instruction to the another storage device before releasing of the first storage region is completed by the first storage region releasing unit.