Provided is a power device. The power device may include a two-dimensional electron gas (2-DEG) layer in a portion corresponding to a gate electrode pattern since a second nitride layer is further formed on a lower portion of the gate electrode pattern after a first nitride layer is formed and thus, may be capable of performing a normally-OFF operation. Accordingly, the power device may adjust generation of the 2-DEG layer based on a voltage of a gate, and may reduce power consumption. The power device may regrow only the portion corresponding to the gate electrode pattern or may etch a portion excluding the portion corresponding to the gate electrode pattern and thus, a recess process may be omissible, a reproducibility of the power device may be secured, and a manufacturing process may be simplified.