To provide a disk array device and the control method capable of improving the reliability of the disk array device and substantially reducing human maintenance loads or the like required for the exchange of a fault disk device or the like.

A disk array controller 2 is provided with a nonvolatile memory 15 for storing the history information of recoverable errors generated in respective disk devices HDD0, HDD1, HDD2 and HDD3, an error generation information calculation means 16 for calculating the error generation frequencies of the respective disk devices and the gradient of the error occurrence frequency based on the history information, a preventive maintenance judgement means 17 for judging the presence/absence of the necessity of the preventive maintenance of the respective disk devices based on the calculated error occurrence frequencies of the respective disk devices and the gradient of the error generation frequency and a preventive maintenance execution means 18 for storing data stored in the disk device for which it is judged that the preventive maintenance is required to a spare disk device HDD4.