A cassette holder of an imaging stand is provided with first and second catch members for catching and holding an electronic cassette from above and below. The first catch member has a multi connector connected to a multi terminal of the electronic cassette. The multi connector is offset with respect to a center line of an imaging surface of the cassette holder. The multi terminal is offset with respect to a center line of an irradiation surface of the electronic cassette in the same direction by the same amount as those of the multi connector. In a state where said electronic cassette mounted on a tray is loaded into the cassette holder, the center line of the irradiation surface coincides with the center line of the imaging surface.