Provided are a nonvolatile memory device and a method of manufacturing the same. A floating gate electrode of the nonvolatile memory device may have a cross-shaped section as taken along a direction extending along a control gate electrode. The floating gate electrode may have an inverse T-shaped section as taken along a direction extending along an active region perpendicular to the control gate electrode. The floating gate electrode may include a lower gate pattern, a middle gate pattern and an upper gate pattern sequentially disposed on a gate insulation layer, in which the middle gate pattern is larger in width than the lower gate pattern and the upper gate pattern. A boundary between the middle gate pattern and the upper gate pattern may have a rounded corner.