In a radiation image read-out apparatus, a stimulable phosphor sheet, on which a radiation image has been stored, is exposed to stimulating rays, which cause the stimulable phosphor sheet to emit light in proportion to the amount of energy stored thereon during its exposure to radiation. The emitted light is detected and photoelectrically converted by a photodetector, and an image signal representing the radiation image is thereby generated by the photodetector. Information corresponding to the amount of energy stored on the stimulable phosphor sheet during its exposure to radiation is inputted from a stored energy amount input device. A light amount adjuster is located in an optical path of the emitted light impinging upon the photodetector in order to adjust the amount of the emitted light impinging upon the photodetector in accordance with the amount of energy stored on the stimulable phosphor sheet, which energy amount is represented by the information having been inputted with the stored energy amount input device.