A method for use with a radiation image detector, including the steps of detecting a faulty signal line having a signal amount less than a predetermined threshold value based on radiation image signals read out from the detector, setting a signal line adjacent to the faulty signal line as an abnormal signal line and a signal line adjacent to the abnormal signal line and having a normal amount of signal as a reference signal line, calculating the difference between a signal read out by the abnormal signal line and a signal read out by the reference signal line as a correction amount, calculating a low frequency component correction amount by removing a high frequency component from the calculated correction amount, and performing a correction on the signal read out by the abnormal signal line by adding the calculated low frequency component correction amount to the signal.
