Inventive concepts provide semiconductor memory devices and methods of fabricating the same. A stack structure and vertical channel structures are provided on a substrate. The stack structure includes insulating layers and gate electrodes alternately and repeatedly stacked on the substrate. The vertical channel structures penetrate the stack structure. Conductive pads are disposed on the vertical channel structures. An etch stopper covers sidewalls of the conductive pads. Pad contacts are disposed on the conductive pads to be in contact with the conductive pads. The pad contacts are further in contact with the etch stopper.