A light detection device includes a photo detector and a circuit board connected to the photo detector by conductive connection parts. In this light detection device, the photo detector includes a substrate, a semiconductor layer provided on one surface of the substrate, a first groove dividing the semiconductor layer into sections for respective pixels, and first electrodes provided on the semiconductor layer and serving as the pixels. Each of the conductive connection part contains indium. Each of the first electrode includes a Ti layer and a Pt layer stacked in this order on the semiconductor layer, and the conductive connection parts are provided on the Pt layers of the first electrodes.