A storage system includes first storage devices to provide storage areas of a first tier and for which a life usage rate is determined based on an erase count and a guaranteed maximum erase count, second storage devices to provide storage areas of a second tier and for which a guaranteed maximum erase count is not specified, and a controller to perform data reallocation between the first tier and the second tier. The controller determines a weight for a read access and a weight for a write access from a host based on life usage rates of the first storage devices, and determines whether to relocate data stored in the second tier to the first tier based on the weight for a read access, the weight for a write access, a read count for the data in a period, and a write count for the data in the period.