Wiring substrates 11 and 12 are positioned on a fixed base 10 in a manner such that there is a step between the wiring substrates, and radiation imaging elements 2 and 3, respectively having scintillators 25 and 35 deposited on photosensitive portions 21 and 31, are respectively mounted on the wiring substrates 11 and 12. The radiation imaging element 2 is positioned so that its setting surface protrudes beyond a radiation incident surface of the radiation imaging element 3, and the photosensitive portion 21 of the radiation imaging element 2 and the photosensitive portion 31 of the radiation imaging element 3 are juxtaposed to a degree to which the portions do not overlap. The photosensitive portion 21 of the radiation imaging element 2 extends close to an edge at the radiation imaging element 3 side and the scintillator 25 of substantially uniform thickness is formed up to this position.