Stimulable phosphor sheets are circulated through an image recording section for recording radiation images on the stimulable phosphor sheets, an image read-out section for scanning the stimulable phosphor sheets by stimulating rays and detecting light emitted thereby upon stimulation, and an erasing section for releasing radiation energy remaining in the stimulable phosphor sheets after image read-out. The level of residual radiation energy in each stimulable phosphor sheet ejected from the erasing section is detected and compared with a predetermined value. When a stimulable phosphor sheet detected to exhibit a residual radiation energy level exceeding the predetermined value is fed to the image recording section, the stimulable phosphor sheet is passed through the image recording section without being subjected to image recording.