A radiographic apparatus comprising: an irradiation unit configured to irradiate a subject with radiation; an aperture (54, 65) configured to regulate an irradiation range of the radiation with which the subject is to be irradiated from the irradiation unit; an aperture controller configured to control an opening area of the aperture; an irradiation area calculation unit configured to calculate an amount of irradiation area of the irradiation range on the basis of the opening area of the aperture (54, 65); and an image data generator configured to detect the radiation that has been transmitted through the subject and to generate image data; an input unit for inputting photographing conditions including an amount of detection area of said generator; characterised by further comprising: a controller configured to compare the amount of irradiation area with the amount of detection area and to control the irradiation of the subject with the radiation by the irradiation unit on the basis of the comparison a radiation amount detection unit configured to detect J the radiation amount of the radiation that has passed through the aperture (54, 65), a region information input unit adapted to input region information relating to a region of the subject that is to be irradiated with the radiation, and a radiation amount calculation unit configured to calculate the amount of the radiation with which the subject has been irradiated on the basis of (i) the radiation amount detected by the radiation amount detection unit and (ii) the region information inputted by the region information input unit and (iii) the image data generated by the image data generator (12, 49), and wherein the controller is configured to prohibit the irradiation of the subiect with the radiation by the irradiation unit when the amount of irradiation area is larger by a predetermined threshold value or more than the amount of detection area. an irradiation unit configured to irradiate a subject with radiation; an aperture (54, 65) configured to regulate an irradiation range of the radiation with which the subject is to be irradiated from the irradiation unit; an aperture controller configured to control an opening area of the aperture; an irradiation area calculation unit configured to calculate an amount of irradiation area of the irradiation range on the basis of the opening area of the aperture (54, 65); and an image data generator configured to detect the radiation that has been transmitted through the subject and to generate image data; an input unit for inputting photographing conditions including an amount of detection area of said generator; a controller configured to compare the amount of irradiation area with the amount of detection area and to control the irradiation of the subject with the radiation by the irradiation unit on the basis of the comparison a radiation amount detection unit configured to detect J the radiation amount of the radiation that has passed through the aperture (54, 65), a region information input unit adapted to input region information relating to a region of the subject that is to be irradiated with the radiation, and a radiation amount calculation unit configured to calculate the amount of the radiation with which the subject has been irradiated on the basis of (i) the radiation amount detected by the radiation amount detection unit and (ii) the region information inputted by the region information input unit and (iii) the image data generated by the image data generator (12, 49), and (i) the radiation amount detected by the radiation amount detection unit and (ii) the region information inputted by the region information input unit and (iii) the image data generated by the image data generator (12, 49), and