Provided is a semiconductor device including a gate structure, a first doped region of a first conductivity type, a plurality of second doped regions of a second conductivity type, a third doped region of the first conductivity type, and a plurality of fourth doped regions of the second conductivity type. The gate structure is located on a substrate. The first doped region is located in the substrate on a first side of the gate structure. The second doped regions are located in the first doped region. The second doped regions are separated from each other. The third doped region is located in the substrate on a second side of the gate structure. The fourth doped regions are located in the third doped region. The fourth doped regions are separated from each other. The second doped regions and the fourth doped regions are disposed alternately.