A radiographing system comprising: a radiation source which irradiates radiation toward a subject; a source control device which controls a driving of the radiation source; a radiological image detection device which receives the radiation transmitted through the subject to detect a radiological image, and has an AEC sensor for detecting the dose of the radiation transmitted through the subject and after an accumulated value of the detected dose reaches an irradiation prohibition threshold value set in advance, performing automatic exposure control to prohibit the irradiation of the radiation; characterized by compensation means for, in a state where the AEC sensor which is placed on an imaging plane of a detection panel of the radiological image detection device is connected to the source control device and used instead of an old AEC sensor which is placed on the front face of the imaging plane of the radiological image detection device between the imaging plane of the detection panel of the radiological image detection device and the radiation source and has a range format or detection principle different from that of the AEC sensor, compensating a detection signal of the AEC sensor as a detection signal corresponding to a detection signal of the old AEC sensor so as to exclude the influence on a detection signal due to a difference in the configuration of an intermediate member disposed between the radiation source and the imaging plane of the detection panel of the radiological image detection device and the difference in the range format or the detection principle in the case of using the AEC sensor instead of the old AEC sensor; and a detection signal I/F which exchanges the detection signal or the accumulated value of the detection signal between the source control device and the radiological image detection device. a radiation source which irradiates radiation toward a subject; a source control device which controls a driving of the radiation source; a radiological image detection device which receives the radiation transmitted through the subject to detect a radiological image, and has an AEC sensor for detecting the dose of the radiation transmitted through the subject and after an accumulated value of the detected dose reaches an irradiation prohibition threshold value set in advance, performing automatic exposure control to prohibit the irradiation of the radiation; characterized by compensation means for, in a state where the AEC sensor which is placed on an imaging plane of a detection panel of the radiological image detection device is connected to the source control device and used instead of an old AEC sensor which is placed on the front face of the imaging plane of the radiological image detection device between the imaging plane of the detection panel of the radiological image detection device and the radiation source and has a range format or detection principle different from that of the AEC sensor, compensating a detection signal of the AEC sensor as a detection signal corresponding to a detection signal of the old AEC sensor so as to exclude the influence on a detection signal due to a difference in the configuration of an intermediate member disposed between the radiation source and the imaging plane of the detection panel of the radiological image detection device and the difference in the range format or the detection principle in the case of using the AEC sensor instead of the old AEC sensor; and a detection signal I/F which exchanges the detection signal or the accumulated value of the detection signal between the source control device and the radiological image detection device.