The present invention provides a radiation detector, a radiographic imaging device, and a radiographic image system that may be easily tested and may precisely detect radiation. Namely, pixels each includes a sensor portion A and a sensor portion B. In imaging pixels, the sensor portion A and the sensor portion B are connected by a connection line, and charges generated in the sensor portion A and in the sensor portion B are read by a TFT switch and output to a signal line. In radiation detection pixels, charges generated in the sensor portion A are read by a TFT switch and output to a signal line. Further, in the radiation detection pixels, the sensor portion B and the signal line are directly connected by a connection line, and the charges generated in the sensor portion B are output to the signal line as they arise.