A power semiconductor device includes a drain region and a source region disposed on a substrate, a gate insulating layer and a gate electrode disposed on the substrate and disposed between the drain region and the source region, a protection layer in contact with a top surface of the substrate and a top surface of the gate electrode, a source contact plug connected to the source region, a drain contact plug connected to the drain region, and a field plate plug in contact with the protection layer, wherein a width of the field plate plug is greater than a width of the source contact plug or a width of the drain contact plug.