A radiation imaging apparatus is provided. The apparatus comprises pixels arranged in an image sensing region, a first and a second detecting elements configured to obtain radiation irradiation information, a first signal line to which a signal from the first detecting element is to be output and a second signal line to which a signal from the second detecting element is to be output, and a signal processing circuit configured to process the signals output from the first and the second detecting elements. The first the second signal lines are arranged in the image sensing region or arranged adjacent to the image sensing region, the first detecting element has a larger region to detect radiation than the second detecting element. The signal processing circuit generates the radiation irradiation information based on the signals from the first and the second signal lines.