The accuracy of predicting the remaining life of a non-volatile memory in which WA occurs is enhanced. A storage controller predicts the remaining lives of SSDs on the basis of the data storage rates of the respective SSDs. When the storage controller determines that a life expectation result on one SSD does not satisfy a target operation period while a life expectation result on another SSD satisfies the target operation period, the storage controller executes extent migration processing of migrating data in any data stored extent to an extent in which data has not been stored, thereby decreasing the data storage rate of the one SSD to extend the life of the one SSD.