A radiation signal processing device including: a reception section that receives as a digital signal a signal representing a detection result from a radiation imaging device that captures an image according to irradiated radiation, and that detects a radiation irradiation amount and outputs the signal representing the detection result; and a conversion section that converts the digital signal representing the detection result received by the reception section into an analog signal recognizable by a radiation irradiation device that irradiates radiation onto the radiation imaging device and stops radiation irradiation in cases in which radiation has reached a specific irradiation amount.