1. A memory system comprising: a non-volatile memory configured to store management information, the management information storing, for each management unit of data, a correspondence relation between a logical address designated by a host apparatus and a physical address on the non-volatile memory; a volatile memory configured to temporarily store the management information; a controller configured to: load the management information stored in the non-volatile memory into the volatile memory at a first timing; store the management information loaded in the volatile memory into the non-volatile memory at a second timing; perform data transmission through the volatile memory between the host apparatus and the non-volatile memory; and perform, based on the management information, data management while updating, in the volatile memory and the non-volatile memory, the management information; and a compression/decompression processor configured to compress the management information in the case where a first condition is satisfied and to decompress the compressed management information in the case where a second condition is satisfied, wherein the compression/decompression processor compresses an address group by replacing data corresponding to a plurality of addresses in the address group with new data, the address group being a group in the management information, the address group being a group in which, for each management unit of the data, the physical addresses and the logical addresses are arranged, wherein the controller is configured to store the compressed management information in the non-volatile memory.