A semiconductor device according to an embodiment of the present disclosure may include: a stack structure including a plurality of first conductive patterns and a plurality of dielectric layers, which are alternately stacked, the stack structure having a stepped structure such that any one of the first conductive patterns further protrudes than the first conductive pattern positioned immediately above it; a plurality of second conductive patterns which are respectively formed over protrusions of the first conductive patterns; a plurality of contact plugs which overlap the plurality of second conductive patterns, respectively, and pass through the overlapping second conductive patterns and the stack structure; and a sealing layer pattern which is interposed between the first conductive patterns and the contact plugs and separates the first conductive patterns from the contact plugs.