A light detection device according to one aspect of the present disclosure includes: a light detector having a main surface and including at least one first detector and at least one second detector disposed along the main surface； a light coupling layer disposed on or apart from the light detector and including a first low-refractive-index layer, a first high-refractive-index layer disposed on the first low-refractive-index layer and including a first grating, and a second low-refractive-index layer disposed on the first high-refractive-index layer, the first high-refractive-index layer having a higher refractive index than the first and second low-refractive-index layers； and a light shielding film disposed on the light coupling layer and including at least one light transmitting region and at least one light shielding region adjacent to the at least one light transmitting region.
