A radiation detector comprises pixel electrodes which collect charges, a photoelectric converting layer which is provided on the pixel electrodes and which converts incident radiation into the charges, and which contains at least one or more kinds of heavy metal halide (AB.sub.n:A=heavy metal, B=halogen, n=either one of 1, 2, and 3) and at least one or more kinds of halogen (B.sub.2) respectively, and an electrode layer which is provided on the photoelectric converting layer opposite to the pixel electrodes.