Patent ID: 8190812

Claim:
A memory system comprising: a volatile first storing unit; a nonvolatile second storing unit in which a plurality of memory cells that can store multi-value data are arranged, the memory cells having a plurality of pages; and a controller that performs data transfer between a host apparatus and the second storing unit via the first storing unit, stores management information including a storage position of the data stored in the second storing unit during a startup operation of the memory system into the first storing unit, and performs, while updating the stored management information, data management in the first and second storing units based on the stored management information, the controller includes a save processing unit that backs up, before writing data in the second storing unit, if data has been already written in a lower order page of a memory cell same as that of a page in which the data is written, the data of the lower order page; and a broken-information-restoration processing unit that restores, when the data in the lower order page is broken, the broken data using the data backed-up by the save processing unit.