A radiation imaging apparatus is provided. The apparatus comprises an image capturing unit and a signal processing unit. The image capturing unit includes a plurality of pixels each including a conversion unit configured to convert radiation into electric charge and a holding unit configured to hold a signal corresponding to electric charge of the conversion unit. The holding unit holds a first signal corresponding to electric charge generated by the conversion unit by one image capturing operation without irradiation with radiation. The signal processing unit generates correction image data based on the plurality of first signals nondestructively read out from the holding unit over a plurality of times while the holding unit holds the first signals, and corrects radiation image data captured by the image capturing unit during irradiation with radiation by using the correction image data.