Image processing, which is constituted of a plurality of processes, is carried out on a radiation image signal. An intermediate image signal obtained in at least one process, which is among the processes other than a last process in the plurality of the processes constituting the image processing, is stored on a predetermined storage medium. In cases where an abnormality occurred during the image processing, a process, in which the abnormality occurred, is discriminated quickly, and a cause of the abnormality is specified quickly.