A semiconductor device includes word lines and interlayer insulating layers alternately stacked over a substrate, vertical channel layers protruding from the substrate and passing through the word lines and the interlayer insulating layers, a tunnel insulating layer surrounding each of the vertical channel layers, a charge trap layer surrounding the tunnel insulating layer, wherein first regions of the charge trap layer between the tunnel insulating layer and the word lines have a thickness smaller than a thickness of second regions thereof between the tunnel insulating layer and the interlayer insulating layers, and first charge blocking layer patterns surrounding the first regions of the charge trap layer.