An X-ray image pickup system (10) includes an X-ray source (16), an image pickup panel (12), a scintillator (13), and an X-ray control unit (14E). The image pickup panel includes a photoelectric conversion element (26), a capacitor (50), a thin film transistor (24), and TFT control units (14A, 14B, 14F). To the photoelectric conversion element (26), scintillation light is projected. The capacitor (50) is connected to the photoelectric conversion element (26), and accumulates charges. The thin film transistor (24) is connected to the capacitor (50). The TFT control units (14A, 14B, 14F) control an operation of the thin film transistor (24). The thin film transistor (24) includes a semiconductor active layer (32) made of an oxide semiconductor. The X-ray control unit (14E) intermittently projects X-ray to the X-ray source (16). The TFT control units (14A, 14B, 14F) cause the thin film transistor (24) to operate when the X-ray is not projected, so as to read out the charges accumulated in the capacitor (50).