A Schottky barrier type radiation detecting element having a compound InxCdyTez comprising indium and cadmium, as means for applying a voltage to a compound semiconductor crystal principally comprising cadmium and tellurium, on one side of the compound semiconductor crystal. Percentage z of tellurium content in the compound InxCdyTez is preferably in the range of 42.9%-50% expressed in terms of the ratio of the number of atoms and percentage y of cadmium content in the compound InxCdyTez is preferably in the range of 0%-10% expressed in terms of the ratio of the number of atoms.