A photodetection element includes a semiconductor layer having, on one surface side, a periodic concave/convex structure that includes periodic convex portions and concave portions and converts light into surface plasmon, and a metal film provided on the one surface side of the semiconductor layer in correspondence to the periodic concave/convex structure, and in the periodic concave/convex structure, a Schottky junction portion that has a Schottky junction with the metal film is provided on a base end side of the convex portion, and a non-Schottky junction portion that does not have a Schottky junction with the metal film is provided on a distal end side of the convex portion.