A semiconductor device includes a substrate, a first P-type well region and a second P-type well region disposed in the substrate, wherein the first P-type well region and the second P-type well region are spaced apart from each other, an N-type source region disposed in the substrate, wherein the N-type source region is disposed spaced apart from the second P-type well region, an N-type drain region disposed in the second P-type well region, an N-type LDD region disposed near the N-type drain region, and a gate insulating layer and a gate electrode on the substrate, wherein the gate electrode partially overlaps the second P-type well region.