Abstract: In a disk array device, a logical device is defined by a plurality of hard disk drives, with the logical device formed by different types of hard disk drives. A logical device setting unit divides the storage area of each of the hard disk drives into parts and performs striping for the divided storage areas of the disk drives. Hence, a logical device can be defined taking into account the capacities of the hard disk drives and can be formed by using hard disk drives of different types.