An image recording sheet and a solid-state image detector are used. The sheet has a stimulable phosphor layer laminated on a base, and the solid-state image detector includes a photoconductive layer containing amorphous selenium as its main component and electrodes disposed on opposite sides of the photoconductive layer. An electric field is applied across the photoconductive layer so that avalanche amplification is obtained within the photoconductive layer. The sheet is scanned under the electric field with stimulating light of wavelength of about 600 nm, and photostimulated luminescence light of wavelength of about 400 nm emitted from the fluorescent layer is incident on the photoconductive layer via an optical guide and a stimulating light cut filter. Electric charge generated within the photoconductive layer is detected by a current detecting circuit, whereby a radiation image signal is obtained.