It is made possible that, in accordance with a plurality of radiographing modes such as the still image radiographing mode and the moving image radiographing mode, the outputs both in the irradiation period and in the non-irradiation period are made to fall within the dynamic range of the radiographing system, whereby an accurate, high-S/N-ratio X-ray radiographic image is obtained. For that purpose, in accordance with the plurality of radiographing modes, an arithmetic operation unit adjusts a power source to control voltage to be applied to a reading circuit unit or an Analogue-Digital conversion unit, such that, in each of the radiographing modes, both an electric signal in the X-ray irradiation period and an electric signal in the X-ray non-irradiation period fall within the dynamic ranges of the reading circuit unit and the Analogue-Digital conversion unit.
