A radiographing system includes a plurality of radiation imaging apparatuses and a composition processing unit which composites a plurality of radiation images acquired from the plurality of radiation imaging apparatuses to generate a long-length image. Each of the radiation imaging apparatuses includes a radiation detecting panel which has a plurality of pixels arrayed in a two-dimensional matrix and converts radiated radiation into an image signal, and a position acquiring unit which acquires positional information by communicating with an external apparatus. A position deciding unit decides an order, in which the plurality of radiation images to be composited by the composition processing unit are composited, based on the positional information acquired by the position acquiring unit.
