The nonvolatile memory device includes a substrate including a first surface and a second surface opposite to the first surface in a first direction; a common source line on the first surface of the substrate; a plurality of word lines stacked on the common source line; a first insulating pattern spaced apart from the plurality of word lines in a second direction crossing the first direction, and in the substrate; an insulating layer on the second surface of the substrate; a first contact plug penetrating the first insulating pattern and extending in the first direction; a second contact plug penetrating the insulating layer, extending in the first direction, and connected to the first contact plug; an upper bonding metal connected to the first contact plug and connected to a circuit element; and a first input/output pad connected to the second contact plug and electrically connected to the circuit element.