The disk array apparatus includes a controller having a communication control unit for accepting a data input/output request, a disk controller unit for controlling a plurality of disk drives, and a cache memory for temporarily storing data transferred between the communication control unit and the disk controller unit. A plurality of cooling fans are provided for cooling the plurality of disk drives. In response to receiving a request, the controller controls the rotational speed of a first cooling fan related to a first disk drive, which is related to the request, and changes an operational mode of the first disk drive related to the request such that the rotational speed of the first cooling fan is increased before the operational mode of the first disk drive is changed.