Abstract: A radiation detector 10 is provided with three optical members 12, 14, 16 arranged so that their entrance end faces 12a, 14a, 16a are placed on a substantially identical plane; a scintillator 18 provided on the entrance end faces 12a, 14a, 16a of the optical members 12, 14, 16; a plurality of CCDs 20 for picking up optical images outputted from exit end faces 12b, 14b, 16b of the optical members 12, 14, 16; and a plurality of lightguide optical members 22 for guiding the optical images outputted from the exit end faces 12b, 14b, 16b of the optical members 12, 14, 16, to the CCDs 20. The optical members 12, 14, 16 are bonded and fixed to each other with an adhesive 24 having the light-absorbing property and spacings between them are set in the range of 10 to 15 &mgr;m. A protective film 26 is provided on the scintillator 18.