A nitride semiconductor based power converting device includes a nitride semiconductor based power transistor, and at least one nitride semiconductor based passive device. The passive device and the power transistor respectively include a channel layer including a first nitride semiconductor material, and a channel supply layer on the channel layer including a second nitride semiconductor material to induce a 2-dimensional electron gas (2DEG) at the channel layer. The passive device may be a resistor, an inductor, or a capacitor.