A semiconductor device includes a semiconductor substrate, a gate structure, a source region, a drain region, and a plurality of field plates. The gate structure is disposed on the semiconductor substrate. The source region and the drain region are disposed in the semiconductor substrate and located at two opposite sides of the gate structure in a first direction respectively. The field plates are disposed on the semiconductor substrate. Each of the field plates is partly located above the gate structure and partly located between the gate structure and the drain region. The gate structure is electrically connected with at least one of the field plates, and the source region is electrically connected with at least one of the field plates.