Provided is a radiographic imaging apparatus including a photon-counting detector that prevents variation in count rate performance by using self-heating of a photon-counting circuit, and improves accuracy in detecting photons. The photon-counting detector is provided with a semiconductor layer configured to generate electrical charge upon receipt of photons of radiation, a photon-counting circuit configured to read current values from pixel electrodes formed on one of the semiconductor surfaces, and a heat amount compensator configured to control an amount of heat of the photon-counting circuit according to a count rate of the photon-counting circuit. The heat amount compensator is activated when the count rate is low so that the amount of heat delivered from the photon-counting circuit when the count is low becomes nearly equal to the amount of heat delivered from the photon-counting circuit when the count rate is high.