An acceleration sensor (25) is installed in an electronic cassette (21). The acceleration sensor detects a shake. When magnitude of the shake, measured using the acceleration sensor, is greater than or equal to a shake detection threshold value, a judging circuit (73) of a shake detecting section (71) turns off a switching element (74). An operation switching section (41a) is disconnected from an irradiation detecting section (61) that detects a start of X-ray irradiation. Thus, an irradiation detection function of the irradiation detecting section is disabled. After a predetermined time, the judging circuit outputs an ON signal to the switching element to turn on the switching element. Thereby, the irradiation detecting section resumes the irradiation detection.
