A radiation detector includes a sensor panel unit, a support table to which the sensor panel unit is attached, and two fixing members. The sensor panel unit includes two sensor panels. The sensor panel has pixels that sense visible light converted from radiation and generate charge. The sensor panel unit has a configuration in which an end portion of one sensor panel and an end portion of the other sensor panel are arranged to overlap each other in a thickness direction. A first fixing member fixes two sensor panels in an overlap region in which the end portions overlap. A second fixing member fixes the sensor panel unit and the support table in the overlap region. The second fixing member at least partially overlaps the first fixing member in the overlap region in a plan view of the sensor panel unit in the thickness direction.