A cassette carrier for containing a cassette incorporating a semiconductor radiation detector includes a rectangular recessed portion formed for containing the cassette with an irradiation surface exposed. The recessed portion is formed by a first frame that forms a side wall of one side thereof and includes a handle that a user holds, and a second frame forming a side wall of another side of the recessed portion. In the side wall formed by the first frame, an opening is provided in an opposite position opposing a connector unit of the cassette with the cassette attached to the recessed portion. The first frame has a space in communication with the opening, and connection/disconnection of an external cable to/from the connector unit is possible through the space with the cassette attached, and the space is large enough to contain an entire connector housing of the external.