A radiation imaging system has a radiation generation device, an FPD cassette, and a console. The console judges whether or not the FPD cassette is in a good communication state repeatedly once every thirty seconds. Upon receiving a radiography order, the console changes repetition intervals from thirty seconds to three seconds, and keeps judging the communication state of the FPD cassette. The repeated judgment is continued until a shutter button is pressed. Upon the press of the shutter button, the radiation generation device emits radiation to carry out radiography.