A non-volatile memory device includes gate electrodes stacked on a substrate, a semiconductor pattern penetrating the gate electrodes and connected to the substrate, and a charge storage layer between the semiconductor pattern and the gate electrodes. The charge storage layer includes a first charge storage layer between the semiconductor pattern and the gate electrodes, a second charge storage layer between the first charge storage layer and the semiconductor pattern, and a third charge storage layer between the first charge storage layer and the gate electrodes. An energy band gap of the first charge storage layer is smaller than those of the second and third charge storage layers. The first charge storage layer is thicker than the second and third charge storage layers.