A radiation image capturing apparatus, comprising: a detection section (p) that includes a plurality of scanning lines and a plurality of signal lines provided so as to cross with each other, and a plurality of radiation detection elements aligned two-dimensionally; switching elements each connected to each of the scanning lines and configured to discharge electric charges accumulated in the radiation detection elements to the signal lines when an on-state voltage is applied; a scanning drive unit configured to sequentially apply the on-state voltage to the plurality of scanning lines and to discharge electric charges accumulated in the radiation detection elements to the signal lines; a readout circuit that converts the electric charges discharged from the radiation detection elements to the signal lines into image data and reads out the image data; and a control unit configured to control the scanning drive unit and the readout circuit to read out the image data to acquire dark image data (Od) in a condition where radioactive irradiation is not performed, afterwards to read out the image data to acquire main image data in a condition where the radioactive irradiation is performed and thereafter to read out the image data to acquire offset data in a condition where the radioactive irradiation is not performed, characterized in that, the radiation image capturing apparatus has a unit for detecting initiation of the radioactive irradiation, after acquiring the dark image data (Od) and before acquiring the main image data, the control unit is configured to repeat an operation that sequentially applies the on-state voltage to the plurality of scanning lines and, after applying the on-state voltage to a scanning line and before applying the on-state voltage to the next scanning line, checking if the unit for detecting the initiation of the radioactive irradiation detects the initiation of the radioactive irradiation, once the initiation of the radioactive irradiation is detected, the control unit stops the operation that is sequentially applying the on-state voltage to the plurality of scanning lines and applies an off-state voltage to all the plurality of scanning lines so as to start the electric charge accumulation mode, and thereafter when reading out the main image data, the control unit is configured to sequentially carry out the readout operation starting at the scanning line next to the scanning line to which the on-state voltage was last applied when application of the on-state voltage was stopped after detecting the initiation of the radioactive irradiation, and the control unit corrects the main image data on the basis of an offset lag part included in the offset data (Olag) acquired by subtracting the dark image data (Od) from the offset data. a detection section (p) that includes a plurality of scanning lines and a plurality of signal lines provided so as to cross with each other, and a plurality of radiation detection elements aligned two-dimensionally; switching elements each connected to each of the scanning lines and configured to discharge electric charges accumulated in the radiation detection elements to the signal lines when an on-state voltage is applied; a scanning drive unit configured to sequentially apply the on-state voltage to the plurality of scanning lines and to discharge electric charges accumulated in the radiation detection elements to the signal lines; a readout circuit that converts the electric charges discharged from the radiation detection elements to the signal lines into image data and reads out the image data; and a control unit configured to control the scanning drive unit and the readout circuit to read out the image data to acquire dark image data (Od) in a condition where radioactive irradiation is not performed, afterwards to read out the image data to acquire main image data in a condition where the radioactive irradiation is performed and thereafter to read out the image data to acquire offset data in a condition where the radioactive irradiation is not performed, characterized in that, the radiation image capturing apparatus has a unit for detecting initiation of the radioactive irradiation, after acquiring the dark image data (Od) and before acquiring the main image data, the control unit is configured to repeat an operation that sequentially applies the on-state voltage to the plurality of scanning lines and, after applying the on-state voltage to a scanning line and before applying the on-state voltage to the next scanning line, checking if the unit for detecting the initiation of the radioactive irradiation detects the initiation of the radioactive irradiation, once the initiation of the radioactive irradiation is detected, the control unit stops the operation that is sequentially applying the on-state voltage to the plurality of scanning lines and applies an off-state voltage to all the plurality of scanning lines so as to start the electric charge accumulation mode, and thereafter when reading out the main image data, the control unit is configured to sequentially carry out the readout operation starting at the scanning line next to the scanning line to which the on-state voltage was last applied when application of the on-state voltage was stopped after detecting the initiation of the radioactive irradiation, and the control unit corrects the main image data on the basis of an offset lag part included in the offset data (Olag) acquired by subtracting the dark image data (Od) from the offset data.