A method of fabricating a nonvolatile memory device includes forming a charge tunneling layer on a semiconductor substrate, forming a charge trapping layer on the charge tunneling layer, forming a charge blocking layer on the charge trapping layer by supplying sequentially a metal source gas and an oxidizing gas onto the charge trapping layer, such that a supplying time of the oxidizing gas is form about 0.1 second to about 1.0 second, and forming a gate electrode layer on the charge blocking layer.