Provided is a nitride semiconductor device including: a substrate having through via holes; first and second nitride semiconductor layers sequentially stacked on the substrate; drain electrodes and source electrodes provided on the second nitride semiconductor layer; and an insulating pattern provided on the second nitride semiconductor layer, the insulating pattern having upper via holes provided on the drain electrodes, wherein the through via holes are extended into the first and second nitride semiconductor layers and expose a bottom of each of the source electrodes.