A photodetection element includes a semiconductor substrate having a principal surface on which detection target light is incident and a rear surface, and including one or a plurality of photodetection regions on the principal surface side, and a light absorption film provided on the rear surface. The light absorption film includes a reflection layer being a metal layer, a resonance layer provided between the reflection layer and the substrate, and a light absorption layer provided between the resonance layer and the substrate. In at least one of a wavelength of the detection target light and a wavelength of spontaneous light, a light transmittance inside the resonance layer is larger than a light transmittance inside the light absorption layer, and a light reflectance on a surface of the reflection layer is larger than a light reflectance on a surface of the resonance layer.