A semiconductor memory device includes first and second memory cell blocks, a block decoder, and first and second block switches. The first and second memory cell blocks have a plurality of memory cells connected in a string structure and are respectively disposed in neighboring planes. The block decoder outputs first and second block select signals in response to pre-decoded address signals and first and second plane select signals, which are respectively enabled according to an enable state of the planes. The first and second block switches connect global word lines to word lines of the first and second memory cell blocks in response to the first and second block select signals, respectively.