A disk array apparatus comprises a casing, a disk drive group configured by a plurality of disk drives, a controller unit configured by a plurality of circuit substrates, a plurality of cooling fans, and backflow prevention members. The plurality of cooling fans is provided so as to be aligned between the disk drive group and the controller unit in the casing. The backflow prevention members are provided so as to protrude on the side of the disk drive group or on the side of the controller unit from between the cooling fans while extending to define a space on the inlet side or the outlet side of the cooling fans.