The present invention relates to a semiconductor memory device and an operating method thereof. The semiconductor memory device may include at least two memory blocks sharing a row decoder, and a peripheral circuit performing a read operation on a selected memory block, between the at least two memory blocks, wherein the peripheral circuit applies a discharge voltage to an unselected memory block, between the at least two memory blocks, for a preset time after a period in which a read voltage is applied to the selected memory block is terminated.