Provided herein is a radiation image capturing apparatus which is able to at least detect initiation of irradiation on its own by using each units already existing in the device without providing new unit, and is able to improve an image quality of a radiological image based on image data. The radiation image capturing apparatus 1 is provided with scanning lines 5, signal lines 6, radiation detection elements 7, scanning drive units 15, switch units 8, reading circuits 17, and the controller 22, and the controller 22 causes the reading circuits 17 to execute readout operations periodically before radiation image capturing operation in a state where each of the switch units 8 is in an off state by applying an off voltage to all the scanning lines 5 from the scanning drive unit 15, causes the reading circuits 17 to repeatedly execute the leaked data readout process in which electric charges q leaked from the radiation detection elements 7 through the switch units 8 are converted into leaked data Dleak, and detects initiation of radioactive irradiation at a point when the read-out leaked data Dleak exceeds a threshold value Dth.
