To provide a radiographic image detector and a radiographic image detection system, capable of reducing consumed electric power in a photographic stand-by mode, while simplifying a switching operation, in the radiographic image detector, capable of saving electric power, and capable of prolonging the service lifetime.

This radiographic image detector 1 for detecting irradiated radiation to acquire radiographic image information is provided with a communication part 28 communicating with an external equipment, and a state control part 29 for controlling a plurality of drive modes that differ in electric power consumptions, and the state control part 29 controls the plurality of drive modes, based on the instruction signal transmitted from the external equipment.