Integrated circuit devices and methods of forming the same are provided. Integrated circuit devices may include a first channel layer including a first surface, a second channel layer that is spaced apart from the first channel layer in a first direction and includes a second surface, a first gate electrode and a second gate electrode. The first surface and the second surface may be spaced apart from each other in the first direction and may face opposite directions. The first channel layer may be in the first gate electrode, and the first gate electrode may be absent from the first surface of the first channel layer. The second channel layer may be in the second gate electrode, and the second gate electrode may be absent from the second surface of the second channel layer.