Abstract: A light receiving element includes a waveguide that includes a waveguide core, a multi-mode interference waveguide that has a width larger than a width of the waveguide, the multi-mode interference waveguide receiving a first light from the waveguide core at a first end, and a photodetection portion that includes a first semiconductor layer and an absorption layer disposed on the first semiconductor layer, the first semiconductor layer including at least one layer and receiving a second light from the multi-mode interference waveguide at a second end, the absorption layer being disposed above the first semiconductor layer and absorbing the second light. A distance from the first end of the multi-mode interference waveguide to the second end of the photodetection portion is longer than 70% of a first length and shorter than 100% of the first length, the first length being a length where self-imaging occurs in the multi-mode interference waveguide.