A highly integrated non-volatile memory device and a method of operating the non-volatile memory device are provided. The non-volatile memory device includes a semiconductor layer. A plurality of upper control gate electrodes are arranged above the semiconductor layer. A plurality of lower control gate electrodes are arranged below the semiconductor layer, and the plurality of upper control gate electrodes and the plurality of lower control gate electrodes are disposed alternately. A plurality of upper charge storage layers are interposed between the semiconductor layer and the upper control gate electrodes. A plurality of lower charge storage layers are interposed between the semiconductor layer and the lower control gate electrodes.