A memory system includes a non-volatile memory constituted by blocks each of which is an erase unit constituted by pages each of which is a write/read unit constituted by memory cells; a random access memory temporarily storing data which is written in or read from the non-volatile memory; and a controller controlling the non-volatile memory and the random access memory, wherein the non-volatile memory includes a main memory area in which the block is divided into first management units respectively specified by logical addresses and a cache area in which the block is divided into second management units respectively specified by logical addresses, a data capacity of one of the second management units is smaller than that of one of the first management units, and the controller changes number of the blocks in the main memory area and number of the blocks in the cache area in the non-volatile memory.