A radiation image sensor comprises (1) an image sensor 1 having a plurality of light receiving elements arranged one or two dimensionally, (2) scintillator 2 having columnar structure formed on the light-receiving surface of this image sensor 1 to convert radiation into light including wavelengths that can be detected by the image sensor 1, (3) a protective film 3 formed so as to cover and adhere to the columnar structure of the scintillator 2, and (4) a radiation-transmittable reflective plate 4 that has a reflective surface 42 disposed to face the image sensor across the protective film 3.