Efficient wear leveling processing is performed in a memory in which the number of times of writing may vary for each of pages that are access units. An address conversion unit performs address conversion between a logical address of a host command and a physical address of the memory for each of management units, the management units each including a plurality of access units of the memory. A write amount measurement unit measures a write amount for each of the access units in each of the management units. The averaging processing unit selects a target management unit from the management units on the basis of the write amount measured by the write amount measurement unit and changes physical address allocation in the address conversion of the target management unit. Then, the averaging processing unit performs processing of averaging write amounts of the access units in the target management unit.