A photodetector element according to an aspect of the present disclosure includes a semiconductor layer with an uneven structure on one surface side that is constituted of projection portions and recess portions, and converts light into surface plasmons, and a metal film that is provided on the one surface side of the semiconductor layer in a manner corresponding to the uneven structure and a Schottky junction is formed between the metal film and the semiconductor layer. The semiconductor layer is constituted of n-type conductive silicon, and the other surface side of the semiconductor layer serves as an incident surface for light. The metal film is constituted of a material including nickel which form the Schottky junction when combined with the semiconductor layer.