A method of fabricating a nonvolatile memory device includes forming a tunnel insulating layer on a semiconductor substrate, forming a charge storage layer on the tunnel insulating layer, forming a dielectric layer on the charge storage layer, the dielectric layer including a first aluminum oxide layer, a silicon oxide layer, and a second aluminum oxide layer sequentially stacked on the charge storage layer, and forming a gate electrode on the dielectric layer, the gate electrode directly contacting the second aluminum oxide layer of the dielectric layer.