A semiconductor device includes interlayer insulating layers and conductive patterns alternately stacked over a pipe gate, a first slit and a second slit penetrating the interlayer insulating layers and the conductive patterns and crossing each other, an etch stop pad groove overlapping an intersection of the first slit and the second slit, arranged in the pipe gate, and connected to the first slit or the second slit, and slit insulating layers filling the first slit, the second slit and the etch stop pad groove.