A semiconductor memory device, which restrains a breakdown of a low-voltage transistor constructing a bit line selecting circuit, is provided. An NAND string unit and transistors (BLSe, BLso, BIASe, BIASo) that construct bit line selecting circuit are formed in a P-well. The transistors are set in a floating state during erasing operation. The voltages of the transistors are increased when an erasing voltage is applied to the P-well. When the erasing voltage is discharged from the P-well, the gates of the transistors are connected to a reference potential via a discharging circuit (410) such that the gate voltage follows the voltage of the P-well to be discharged.