To provide a calibration method for a radiation image photographing device which can reduce variations in image data caused by variations in components of each A/D conversion circuit, in radiation images.

The calibration method for a radiation image photographing device includes: a radiation irradiation process for irradiating the radiation image photographing device 1 respectively with a predetermined plurality of doses Rhigh, Rlow of radiation on the lower dose side than half the maximum dose of radiation detectable by radiation detection elements 7; a read conversion process for converting image data of a plurality of analog values obtained by reading each charge accumulated in the radiation detection elements 7 by irradiation with the plurality of doses of radiation, into image data Gi of a plurality of digital values for each A/D conversion circuit 20; and a correction value calculation process for, based on the image data Gi of the plurality of digital values converted for each A/D conversion circuit 20, calculating correction values q with respect to the image data of the digital values for each A/D conversion circuit 20.