A center position of a female connector is located near to a rear surface of a housing compared with a center position of the housing in a thickness direction of the housing of an electronic cassette. An inclined surface, which is inclined relative to a side surface and the rear surface of the housing, is formed between the side surface and the rear surface. The female connector is formed on the inclined surface. Therefore, it is possible to attach an outer grid provided with a longer side panel to the housing, in comparison with the case where the center position of the female connector is made coincident with the center position of the housing in the thickness direction of the housing, without requiring any processing.