A radiation detecting apparatus capable of obtaining good images including decreased noises includes a plurality of pixels, each having a photoelectric conversion element for converting an incident radiation into an electric signal and a a first switch element connected to the photoelectric conversion element and a second switch element being not connected to the conversion element; a first signal line; a second signal line; and a drive line, wherein the first switch element has a first main electrode connected electrically to the first signal line, a second main electrode connected electrically to the photoelectric conversion element, and a gate electrode connected electrically to the drive line, the second switch element has a first main electrode connected to the second signal line and a gate electrode connected electrically to the drive wiring common to the first switch element, and a differential means for outputting a signal corresponding to a difference between outputs from the first and second switch elements.