1 A two-dimensional radiation image detector characterized in that the top surface of a scintillator sheet which generates fluorescence upon incidence of a radiation has grooves cut at predetermined spacings in a horizontal and a vertical direction to a depth at least one half the thickness of the scintillator sheet, with optical fiber bundles being placed in the vertical grooves and a fluorescence reflector buried in the horizontal grooves, that optical fiber bundles are arranged on either the top or the bottom surface of the scintillator sheet or on both surfaces in a transverse direction normal to the optical fiber bundles within the vertical grooves to make a group of detection pixels that are separated by the horizontal and vertical grooves, and that the fluorescence generated by stimulation with the radiation launched into the detection pixels is detected by the optical fiber bundles placed within the vertical grooves in the scintillator sheet and the optical fiber bundles arranged on either the top or the bottom surface of the scintillator sheet or on both surfaces, thereby producing a two-dimensional radiation image.