A semiconductor device is provided. The semiconductor device includes a gate on a substrate, a source region at a first side of the gate, a first conductive type body region under the source region, a second conductive type drain region at a second side of the gate, a device isolation region in the substrate between the source region and the drain region and overlapping part of the gate, and a first buried layer extending in a direction from the source region to the drain region, the first buried layer under the body region, overlapping part of the device isolation region, and not overlapping the drain region.