One surface of a stimulable phosphor sheet supported at a position for image recording is exposed to radiation, and a radiation image is stored on the stimulable phosphor sheet. Image readout is performed from the side of the other surface of the stimulable phosphor sheet supported at the position for image recording. Energy remaining on the stimulable phosphor sheet is then released by irradiating erasing light to an entire area of the stimulable phosphor sheet with a sheet-shaped erasing light source, which has uniform transmissivity to radiation and is located close to the one surface of the stimulable phosphor sheet supported at the position for image recording.