A nonvolatile memory device includes a substrate including a cell region, contact regions and dummy contact regions. The contact regions and the dummy contact regions alternately are disposed. A plurality of word lines stacked at the cell region of the substrate and contact groups stacked at the contact regions and the dummy contact regions of the substrate. The contact groups include a plurality of pad layers being coupled to the word lines, and each of the contact groups has stepped structure disposed at a corresponding contact region.