Provided herein may be a semiconductor memory device. The semiconductor memory device may include: a memory cell array including a plurality of memory blocks; a peripheral circuit configured to apply an erase voltage to a source line and a plurality of select lines of a selected memory block among the plurality of memory blocks during an erase operation; and a control logic configured to control the peripheral circuit to form a trap in an area below at least one of a plurality of source select transistors included in the selected memory block, before the erase voltage is applied to the selected memory block.