To display radiation image data subjected to offset correction quickly after switching of drive from a fluoroscopic photographing mode to a still image photographing mode.

A radiation image photographing device includes: a first photographing unit 101 that photographs dark image data in a fluoroscopic photographing mode without irradiation with radiation; a second photographing unit 102 that photographs radiation image data in a still image photographing mode with irradiation with radiation; a resolution conversion unit 103 that reduces the resolution of the radiation image data; and an offset correction unit 105 that performs offset correction to the radiation image data with the reduced resolution on the basis of the dark image data.