An X-ray imaging system performs pre-exposure and main exposure to take a single X-ray image. In the pre-exposure, an AEC circuit reads out a dose detection signal outputted from a detection pixel, and compares an integral value of the dose detection signal with a threshold value. When the integral value has reached the threshold value, the AEC circuit stops X-ray emission. A main exposure condition determination unit determines main irradiation time, being one item of a main exposure condition, based on irradiation time in the pre-exposure, an integral dose in the pre-exposure, and a necessary dose required for production of the X-ray image. After that, the main exposure is performed immediately with the determined main irradiation time. Normal pixels perform a charge accumulation operation continuously from the start of the pre-exposure to the end of the main exposure, and the X-ray image is produced from accumulated electric charge.
