A radiation imaging system includes a holding unit configured to hold a plurality of radiation imaging apparatuses configured to convert radiation emitted onto the plurality of radiation imaging apparatuses into image signals. The radiation imaging system is configured to obtain a long radiographic image based on the image signals respectively from the plurality of radiation imaging apparatuses. The holding unit is configured to hold the plurality of radiation imaging apparatuses having imaging areas of different sizes, in such a manner that the plurality of radiation imaging apparatuses is partially overlapped with each other spatially, by a predetermined overlapping area as viewed from a radiation incident side.