A radiation imaging apparatus includes a reset control unit configured to perform reset scanning to sequentially discharge charges accumulated in pixels an irradiation detection unit configured to detect a start of radiation irradiation based on charges discharged by the reset scanning an imaging control unit configured to perform control to stop the reset scanning in accordance with detection of the start of irradiation and obtain an image signal by reading out charges accumulated in the pixels a generation unit configured to generate image data based on the image signal except for an image signal from a pixel on which the reset scanning is performed during the radiation irradiation and an output unit configured to output the image data to an external apparatus.
