A memory system includes a DRAM 20 that performs writing and readout in a unit equal to or smaller than a cluster, a NAND memory 10 that performs writing and readout in a page unit, and a management table group in which management information including storage locations of data stored in the DRAM 20 and the NAND memory 10 is stored. When a readout request is received from the outside, a data managing unit 120 notifies, when an unwritten logical address area is present in a storage area of the NAND memory to which a logical address area requested to be read out is mapped, fixed data stored in the DRAM 20 to the outside in association with the logical address area.