A radiation imaging apparatus includes an imaging unit having a pixel array of pixels, and a signal processing unit for processing a signal from the imaging unit. Each pixel includes a conversion element for converting radiation into electrical signal and a reset unit for resetting the conversion element, the signal processing unit generates radiation image based on first image corresponding to electrical signal converted by the conversion unit of each pixel in a first period, and second image corresponding to electrical signal converted by the conversion element of each pixel in a second period which starts after start of the first period and ends before end of the first period, and in each pixel, the conversion element is not reset by the reset unit in the first period.