A semiconductor memory device including a first semiconductor layer, a second semiconductor layer, and a third semiconductor layer between the first and second semiconductor layers, gate electrodes arranged on the second semiconductor layer and spaced apart from each other in a first direction perpendicular to an upper surface of the second semiconductor layer, and channel structures penetrating the first, second and third semiconductor layers and the gate electrodes, each respective channel structure of channel structures including a gate insulating film, a channel layer, and a buried insulating film, the gate insulating film including a tunnel insulating film adjacent to the channel layer, a charge blocking film adjacent to the gate electrodes, and a charge storage film between the tunnel insulating film and the charge blocking film, and the charge storage film including an upper cover protruding toward the outside of the respective channel structure.