A radiographic image detector to detect radiation applied thereto and obtain radiographic image information, includes: an internal power supply to supply power to drive units at least upon imaging; a communication unit to perform communication with an external device; a connection terminal connectable to a connection unit which performs at least one of charging of the internal power supply and the communication with the external device; a storing unit to store at least one of an image and information; a connection detecting unit to detect whether the connection terminal is connected to the connection unit; a state checking unit to check a state of each unit; and a control unit to control the state checking unit such that the state checking unit checks the state of each unit when the connection detecting unit has detected that the connection unit is connected to the connection terminal or disconnected therefrom.