A nonvolatile memory device including a substrate extending in a first direction, a ground selection line extending in the first direction on the substrate, a plurality of word lines stacked sequentially on the ground selection line and extending in the first direction, a landing pad spaced apart from the ground selection line and the plurality of word lines in the first direction, a rear contact plug connected to a lower face of the landing pad and extending in a second direction intersecting the first direction, a front contact plug connected to an upper face of the landing pad opposite the lower face and extending in the second direction, an input/output pad electrically connected to the rear contact plug, and an upper bonding pad electrically connected to the front contact plug and connected to at least a part of a plurality of circuit elements of the nonvolatile memory device.