A detectable range for an output signal corresponding to charge stored at a pixel is widened in a radiation detector based on an APS method. A resistor (42) is connected to a region between a pixel (12) and a signal readout circuit (21) in a signal output line (51). The resistor (42) is set so as to draw, from the signal output line (51), a current approximately equivalent to a bias current which flows to an amplifier transistor (16) when no charge is stored in a charge storage part (14).