To always transfer correct data to a host by restructuring correct host data even when a contradiction in consistency is found by a read parity check.

A device of RAID(Redundant Arrys of Inexpensive Disk) level 3 adds CRC(Cyclic Redundancy Check information) to host data by a CRC addition processing part 11, and a disk array controller 4 divides the data by a disk array controller 4, generates parity from the divided data, and stores it in disk drives 6-1-6-n. At read time, a parity processing part 19 makes a read parity check and if there is a contradiction in consistency, the disk array controller 4 assumes that wrong data are stored in data disk drives in one- different order, restructures host data from divided data and parity of other disk drives except the disk drive, and makes a CRC check on the host data, thereby employing the data as correct host data on condition that the data are consistent.