Provided is a semiconductor structure including a first guard ring and a second guard ring. The first guard ring is located in a substrate. The first guard ring includes first doped regions and second doped regions arranged alternately. The first doped regions and the second doped regions have different conductivity types. The second guard ring is located adjacent to the first guard ring. The second guard ring includes third doped regions and fourth doped regions arranged alternately, and mask layers. Each of the third doped regions corresponds to each of the second doped regions. Each of the fourth doped regions corresponds to each of the first doped regions. The third doped regions and the first doped regions have the same conductivity type and are disposed in a staggered manner. The mask layers are respectively disposed on the substrate between the third doped regions and the fourth doped regions.