Example embodiments include nonvolatile memory devices that have good operation performance and may be made in a highly integrated structure, and methods of operating the same. Example embodiments of the nonvolatile memory devices include a substrate electrode, and a semiconductor channel layer on the substrate electrode, a floating gate electrode on the substrate electrode, wherein a portion of the floating gate electrode faces the semiconductor channel layer, a control gate electrode on the floating gate electrode, and wherein a distance between a portion of the floating gate electrode and the substrate electrode is smaller than a distance between the semiconductor channel layer and the substrate electrode wherein charge tunneling occurs.