According to an aspect, a detection device includes: a substrate; a plurality of photoelectric conversion elements provided to the substrate; a plurality of transistors provided corresponding to each of the photoelectric conversion elements; and a plurality of scan lines that extend in a first direction. A plurality of detection elements each include the photoelectric conversion element and the transistors provided so as to overlap the photoelectric conversion element. The detection elements include a first detection element and a second detection element adjacent in a second direction intersecting the first direction, and one of the scan lines is provided between the first detection element and the second detection element and is coupled to the first detection element and the second detection element.