A cassette that is detected as being in an abnormally loaded state by a cassette loader is fed through a first processor, a second processor, a third processor, and a fourth processor to a fifth processor, and then discharged into a cassette storage unit. Similarly, a cassette which is detected as failing to eject a stimulable phosphor panel by the second processor is also discharged into the cassette storage unit. A cassette in a normal state ejects a stimulable phosphor panel in the second processor, and the ejected stimulable phosphor panel is processed in a main unit. The processed stimulable phosphor panel is stored back into the cassette, which is then unloaded into a cassette unloader.