An avalanche photodiode includes: a first contact layer; a light absorbing layer located on the first contact layer and having a multi-quantum well structure; a first electric field control layer located on the light absorbing layer; and a carrier multiplication layer located on the first electric field control layer. At least one of the multi-quantum well structure includes a well layer that includes Ga1-xAlxN (0≤X≤0.3), and a barrier layer that includes Ga1-xAlxN (0.7≤X≤1) and a doping portion doped with a p-type dopant.