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, that a fluorescence reflector is buried in the 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 to produce a two-dimensional radiation image.