A radiation detector of this invention has a barrier layer on the upper surface of a high resistance film along the outer edge of a common electrode, which enables prevention of a chemical reaction between an amorphous semiconductor layer and a curable synthetic resin. The barrier layer is adhesive to the curable synthetic resin film, and this can prevent strength being insufficient, such that temperature changes cause separation in interfaces between the barrier layer and curable synthetic resin film, thereby reducing the effect of inhibiting warpage and cracking. The material for the barrier layer is an insulating material not including a substance that would chemically react with the amorphous semiconductor layer. This can prevent components of the material for the barrier layer from chemically reacting with the semiconductor layer. Consequently, creeping discharge at the outer edge of the common electrode where electric fields concentrate can be prevented.