A radiographic imaging device comprising: a radiation detector including a plurality of pixels, each including a sensor portion that generates charges according to an amount of irradiated radiation and accumulates the generated charges, and a switching element that reads the charges from the sensor portion based on a control signal and outputs electrical signals according to the charges into a signal line; and at least one radiation sensor portion (150, 174) that is different from the sensor portions, wherein the at least one radiation sensor portion is at least one sensor portion that is provided externally to the radiation detector and disposed on a non-irradiated, bottom surface of the radiation detector on which a scintillator is not disposed; a detection means that is configured to perform a detection operation that detects a radiation irradiation start in at least one of a case in which an electrical signal caused by charges generated in the sensor portions satisfies a specific irradiation detection condition, or a case in which an electrical signal caused by charges generated in one of the at least one radiation sensor portion (150, 174) satisfies a specific irradiation detection condition; and a control means that is configured to determine whether or not noise caused by external disturbance has occurred based on an electrical signal caused by charges generated in the at least one radiation sensor portion (150, 174) after the detection means has detected the radiation irradiation start, and in a case in which the noise has occurred, that is configured to control to stop a current operation of the radiation detector, and control such that the detection operation is performed by the detection means. a radiation detector including a plurality of pixels, each including a sensor portion that generates charges according to an amount of irradiated radiation and accumulates the generated charges, and a switching element that reads the charges from the sensor portion based on a control signal and outputs electrical signals according to the charges into a signal line; and at least one radiation sensor portion (150, 174) that is different from the sensor portions, wherein the at least one radiation sensor portion is at least one sensor portion that is provided externally to the radiation detector and disposed on a non-irradiated, bottom surface of the radiation detector on which a scintillator is not disposed; a plurality of pixels, each including a sensor portion that generates charges according to an amount of irradiated radiation and accumulates the generated charges, and a switching element that reads the charges from the sensor portion based on a control signal and outputs electrical signals according to the charges into a signal line; and at least one radiation sensor portion (150, 174) that is different from the sensor portions, wherein the at least one radiation sensor portion is at least one sensor portion that is provided externally to the radiation detector and disposed on a non-irradiated, bottom surface of the radiation detector on which a scintillator is not disposed; a detection means that is configured to perform a detection operation that detects a radiation irradiation start in at least one of a case in which an electrical signal caused by charges generated in the sensor portions satisfies a specific irradiation detection condition, or a case in which an electrical signal caused by charges generated in one of the at least one radiation sensor portion (150, 174) satisfies a specific irradiation detection condition; and a control means that is configured to determine whether or not noise caused by external disturbance has occurred based on an electrical signal caused by charges generated in the at least one radiation sensor portion (150, 174) after the detection means has detected the radiation irradiation start, and in a case in which the noise has occurred, that is configured to control to stop a current operation of the radiation detector, and control such that the detection operation is performed by the detection means.