A semiconductor memory device includes a memory array, a row selection circuit and a bit line selection circuit. The memory array is composed of a plurality of cell units, wherein each cell unit has memory cells connected in series. The row selection circuit selects the memory cells in a row direction of the cell units, and the bit line selection circuit selects a bit line from an even bit line and an odd bit line coupled to the cell units. The bit line selection circuit includes a first selection part including selection transistors for selectively coupling the even or odd bit line to a sensor circuit and a second selection part including bias transistors for selectively coupling the even or odd bit line to a voltage source providing biases, wherein the bias transistors and the memory cells are formed in a common well.