The control device allows a step of reading the leak data and a step of resetting each radiation detection element to be executed alternately before radiation image capturing. When the data exceed a threshold value, the irradiation start is detected and electric charge is accumulated. Then, the step of reading the image data is executed. After this, the control device further allows a step of reading the leak data and a step of resetting each radiation detection element to be performed alternately at the same cycle time as that in the step of reading the leak data and the step of resetting each radiation detection element performed before detecting the irradiation start. After transfer to the electric charge accumulation state, the control device further permits a step of reading the offset data to be executed at the same cycle time as that in the step of reading the image data.