US Patent 9799406 Memory system

A memory system includes a memory device, and a controller which controls the memory device. The memory device includes a plurality of memory cells capable of rewriting data, a plurality of word lines connected to the plurality of memory cells, a page including the plurality of memory cells connected to the same word line, a plane including a plurality of pages, a memory cell array including a plurality of planes, and a plurality of word line drivers which apply voltages to the plurality of word lines, and a plurality of switches provided for each plane and which assigns the word line drivers to the word lines.