A radiation imaging device 12 has a phosphor film 8; a photoelectric conversion portion 13 including an upper electrode 6, a lower electrode 2, and a photoelectric conversion film 4 disposed between the electrodes; a signal output portion 14 including a field effect thin film transistor 10 having an active layer 24 formed from an amorphous oxide and that outputs a signal corresponding to electric charges generated by the photoelectric conversion portion; and a substrate 1 on which the signal output portion, the photoelectric conversion portion and the phosphor film are formed in this order. Each of pixel portions is made up of the signal output portion, the photoelectric conversion portion and the phosphor film, and the signal output portion and the photoelectric conversion portion in each of the pixel portions are formed so as to have an overlapping portion in a thickness direction.