To provide a radiation image photographing system improving a compression ratio when compressing image data acquired in radiation image photography, and allowing prompt display of a preview image.

In this radiation image photographing system 50, when difference data ΔD between pieces of thinned-out data Dt are compressed and transmitted from a radiation image photographing apparatus 1, a console 58 expands them to restore the original thinned-out data Dt, and displays the preview image based on the thinned-out data Dt on a display part 58a. When the difference data ΔD between pieces of image data D are compressed and transmitted from the radiation image photographing apparatus 1, the console 58 generates a radiation image based on the original image data D restored by expanding the difference data ΔD. In the radiation image photographing apparatus 1 or the console 58, a reference different from a reference of the compression used for compression processing of the difference data ΔD related to the image data D is prepared as the reference of the compression used for the compression processing of the difference data ΔD related to the thinned-out data Dt.