According to an aspect, a detection device includes a substrate and a plurality of photodiodes arranged on the substrate. Each of the photodiodes comprises a p-type semiconductor layer, an i-type semiconductor layer, and an n-type semiconductor layer stacked on the substrate. Each of the photodiodes includes a plurality of first regions in each of which the p-type semiconductor layer, the i-type semiconductor layer, and the n-type semiconductor layer are stacked so as to be directly in contact with one another, and a second region in which at least the p-type semiconductor layer and the i-type semiconductor layer are stacked so as to be separate from each other. Adjacent first regions included in the plurality of first regions are coupled together by at least the p-type semiconductor layer.