A semiconductor device is provided. The semiconductor device includes a stack structure that includes a plurality of dielectric layers spaced apart from each other on a substrate, a plurality of electrodes interposed between the plurality of dielectric layers, and a plurality of stopper layers interposed between the plurality of dielectric layers; and a vertical channel structure that penetrates the stack structure. Each of the plurality of electrodes and the plurality of stopper layers is disposed in a corresponding empty space interposed between the plurality of dielectric layers, the plurality of stopper layers includes a first stopper layer and a second stopper layer that is interposed between the first stopper layer and the substrate, and at least one of the plurality of electrodes is interposed between the first stopper layer and the second stopper layer.