An image-data reading unit reads image data stored after radiation irradiation is performed from a radiation detector. An offset-data reading unit reads offset data in a case in which no radiation irradiation is performed from the radiation detector. After radiation irradiation is performed, a drive control section drives the image-data reading unit so that the image-data reading unit reads image data. Then, the drive control section drives the offset-data reading unit so that the offset-data reading unit reads offset data before the next irradiation is performed. In a period in which radiation irradiation is not performed, the image data and the offset data that have been read are sent to an image-handling section. The image data and the offset data that have been received by a data sending/receiving unit are subjected to subtraction processes by an image processing unit.
