According to an embodiment, a memory system comprising: a non-volatile memory including a plurality of memory cells each capable of storing at least a first bit and a second bit, and configured to calculate third soft bit data based on a logical sum calculation using at least first soft bit data corresponding to the first bit and second soft bit data corresponding to the second bit; and a memory controller configured to restore the first soft bit data and the second soft bit data based on at least first hard bit data corresponding to the first bit, second hard bit data corresponding to the second bit, and the third soft bit data.