To provide a radiation image generating system and a radiation image detector capable of keeping electric power consumption of an internal electric supply means to the minimum and obtaining a high accurate image suitable of diagnosis in the case where a radiation image is photographed by using the radiation image detector capable of driving with the internal electric supply means.

This system includes an FPD cassette 2 having an electric source means for supplying electric power to each functional unit including a battery 28 and a cassette control unit 30 for controlling the electric power supply with the electric source means, and a console 5 having a communication unit 55 for transmitting image order information, and the cassette control unit 30 determines whether an electric supply condition to each functional unit with the electric source means is kept in an imaging mode capable of imaging or an imaging stop mode for stopping the imaging from the image order information corresponding to these images during changing to a next imaging after one imaging is finished and controls the electric supply to each functional unit with the electric source means for being the electric supply condition corresponding to the determined mode.