A radiation image capturing apparatus, comprising: a detecting section that includes: a plurality of scanning lines and a plurality of signal lines arranged to intersect with each other, and a plurality of radiation detection elements that are two-dimensionally aligned, each element being individually aligned_in respective regions partitioned by the plurality of scanning lines and the plurality of signal lines; a scanning drive unit that applies a voltage to each of the scanning lines while switching the voltage between an on voltage and an off voltage; switch units each connected to each of the scanning lines, the switch units configured to discharge electric charges accumulated in the radiation detection elements to the signal lines when the on voltage is applied thereto through the scanning lines, and accumulate electric charges in the radiation detection elements when an off voltage is applied thereto through the scanning lines; reading circuits which convert the electric charges discharged to the signal lines from the radiation detection elements into image data and reads out the image data during an image data readout process in which the image data is read out from the radiation detection elements; and a controller which controls at least the scanning drive unit and the reading circuits and causes the same to execute the image data readout process from the radiation detection elements, wherein the controller causes the reading circuits to periodically perform a readout operation before radiation image capturing operation in a state where each of the switch units is in an off state by applying the off voltage to all of the scanning lines from the scanning drive unit, causes the reading circuits to repeatedly execute a leaked data readout process in which the electric charges leaked from the radiation detection elements through the switch units are converted into leaked data, and detects initiation of irradiation at a point when the read-out leaked data exceeds a threshold value, and wherein, in the leaked data readout process repeatedly executed before the radiation image capturing operation, the controller causes the scanning drive unit to apply the on voltage to each of the scanning lines to execute a reset process for removing an excessive electric charge from each of the radiation detection elements, between the leaked data readout process and the next leaked data readout process, and wherein, when applying the on voltage to each of the scanning lines in the reset process before the radiation image capturing operation, the scanning drive unit executes the reset process-by applying the on voltage to the scanning lines other than the scanning lines which are respectively, in the detecting section, adjacent to the scanning lines to which the on voltage was applied in the previous reset process. a detecting section that includes: a plurality of scanning lines and a plurality of signal lines arranged to intersect with each other, and a plurality of radiation detection elements that are two-dimensionally aligned, each element being individually aligned_in respective regions partitioned by the plurality of scanning lines and the plurality of signal lines; a scanning drive unit that applies a voltage to each of the scanning lines while switching the voltage between an on voltage and an off voltage; a plurality of scanning lines and a plurality of signal lines arranged to intersect with each other, and a plurality of radiation detection elements that are two-dimensionally aligned, each element being individually aligned_in respective regions partitioned by the plurality of scanning lines and the plurality of signal lines; a scanning drive unit that applies a voltage to each of the scanning lines while switching the voltage between an on voltage and an off voltage; switch units each connected to each of the scanning lines, the switch units configured to discharge electric charges accumulated in the radiation detection elements to the signal lines when the on voltage is applied thereto through the scanning lines, and accumulate electric charges in the radiation detection elements when an off voltage is applied thereto through the scanning lines; reading circuits which convert the electric charges discharged to the signal lines from the radiation detection elements into image data and reads out the image data during an image data readout process in which the image data is read out from the radiation detection elements; and a controller which controls at least the scanning drive unit and the reading circuits and causes the same to execute the image data readout process from the radiation detection elements, wherein the controller causes the reading circuits to periodically perform a readout operation before radiation image capturing operation in a state where each of the switch units is in an off state by applying the off voltage to all of the scanning lines from the scanning drive unit, causes the reading circuits to repeatedly execute a leaked data readout process in which the electric charges leaked from the radiation detection elements through the switch units are converted into leaked data, and detects initiation of irradiation at a point when the read-out leaked data exceeds a threshold value, and