A nonvolatile memory device having a cell over periphery (COP) structure includes a first sub memory plane and a second sub memory plane disposed adjacent to the first sub memory plane a row direction. A first vertical contact region is disposed in the cell region of the first sub memory plane and a second vertical contact region is disposed in the cell region of the second sub memory plane. A first overhead region is disposed in the cell region of the first sub memory plane and adjacent to the second vertical region in the row direction, and a second overhead region is disposed in the cell region of the second sub memory plane and adjacent to the first vertical region in the row direction. Cell channel structures are disposed in a main region of the cell region.