A radiation imaging apparatus comprises at least one first detection element including a first conversion element configured to convert radiation into an electrical signal and a first switch configured to connect an output from the first conversion element to a first signal line, at least one second detection element including a second conversion element configured to convert radiation into an electrical signal and a second switch configured to connect an output from the second conversion element to a second signal line, a readout unit configured to read out signals appearing on the first signal line and the second signal line, and a signal processing circuit configured to process a signal read out from the readout unit. A sensitivity of the first conversion element for the radiation is set to be different from a sensitivity of the second conversion element for the radiation.