A radiation image capturing apparatus is provided, which is capable of improving detection efficiency for detecting initiation of radioactive irradiation by the apparatus itself.The radiation image capturing apparatus 1 is provided with a scanning drive unit 15 which sequentially applies an ON voltage to respective scanning lines 5 during a readout process to read out image data d, D from radiation detection elements 7. From the time before radiation image capturing operation, a controller 22 controls the scanning drive unit 15 to sequentially applies the ON voltage to the respective scanning lines 5 and executes the readout process for the image data d from the radiation detection elements 7. The controller 22 detects that the radioactive irradiation is initiated when the image data d exceeds a threshold value dth, and controls that ON time, which is a period from time of applying the ON voltage to the scanning lines 5 from the scanning drive unit 15 during the readout process for the image data d before radiation image capturing operation until time of switching the voltage to an OFF voltage, becomes longer than ON time during a readout process for image data D after finishing the radioactive irradiation.
