A radiographic system comprising: a plurality of radiation detection apparatuses (120, 122, 124), which overlap each other, configured to detect X-rays and output a plurality of radiation images, each of the plurality of radiation detection apparatuses (120, 122, 124) having a radiation detection panel, which detects X-rays in an effective pixel region, and having an outer casing (160, 162); a combining processor configured to generate a long-size image by combining the plurality of radiation images, obtained by the plurality of radiation detection apparatuses which overlap each other, characterized in that the radiographic system further comprises: an image correction unit configured to correct a defective region, generated in the long-size image, using a pixel value distribution of a normal region, which is spatially adjacent to the defective region, said defective region including structure information of the radiation detection apparatuses in a region in a range in a radiation image, obtained by a radiation detection apparatus disposed in a position on the back side of the radiation detection apparatuses, from an end portion of the effective pixel region of the said radiation detection apparatus disposed in a position on the back side of the radiation detection apparatuses, to an end portion of the outer casing of a radiation detection apparatus overlapping with said radiation detection apparatus on the back side of the radiation detection apparatuses, said defective region in the long-size image corresponding to a region in which at least two of the plurality of radiation detection apparatuses overlap with each other; and a gradation processor configured to convert gradation of the long-size image that has been corrected by the image correction unit. a plurality of radiation detection apparatuses (120, 122, 124), which overlap each other, configured to detect X-rays and output a plurality of radiation images, each of the plurality of radiation detection apparatuses (120, 122, 124) having a radiation detection panel, which detects X-rays in an effective pixel region, and having an outer casing (160, 162); a combining processor configured to generate a long-size image by combining the plurality of radiation images, obtained by the plurality of radiation detection apparatuses which overlap each other, characterized in that the radiographic system further comprises: an image correction unit configured to correct a defective region, generated in the long-size image, using a pixel value distribution of a normal region, which is spatially adjacent to the defective region, said defective region including structure information of the radiation detection apparatuses in a region in a range in a radiation image, obtained by a radiation detection apparatus disposed in a position on the back side of the radiation detection apparatuses, from an end portion of the effective pixel region of the said radiation detection apparatus disposed in a position on the back side of the radiation detection apparatuses, to an end portion of the outer casing of a radiation detection apparatus overlapping with said radiation detection apparatus on the back side of the radiation detection apparatuses, said defective region in the long-size image corresponding to a region in which at least two of the plurality of radiation detection apparatuses overlap with each other; and a gradation processor configured to convert gradation of the long-size image that has been corrected by the image correction unit. an image correction unit configured to correct a defective region, generated in the long-size image, using a pixel value distribution of a normal region, which is spatially adjacent to the defective region, said defective region including structure information of the radiation detection apparatuses in a region in a range in a radiation image, obtained by a radiation detection apparatus disposed in a position on the back side of the radiation detection apparatuses, from an end portion of the effective pixel region of the said radiation detection apparatus disposed in a position on the back side of the radiation detection apparatuses, to an end portion of the outer casing of a radiation detection apparatus overlapping with said radiation detection apparatus on the back side of the radiation detection apparatuses, said defective region in the long-size image corresponding to a region in which at least two of the plurality of radiation detection apparatuses overlap with each other; and a gradation processor configured to convert gradation of the long-size image that has been corrected by the image correction unit.