To reduce an exposed dose applied to a subject, compared to a conventional radiographic imaging apparatus, in a radiographic imaging apparatus prepared for long-length imaging of a range larger than a detecting range of a radiation image detecting means.

A computer 4 for controlling the entire radiographic imaging system 1 relates a site to be imaged of the subject P and a position of a radiographic imaging part 15 and varies imaging conditions for each site of the subject P. When a plurality of radiation images obtained by imaging are synthesized, the computer 4 synthesizes the plurality of radiation images after approximating density or contrast of each image by adjusting the density of the radiation image for each of the plurality of radiation images to be synthesized.