To accurately detect a marker indicating the position of a subject when capturing a phase contrast image using a fringe scanning method.

On the outer periphery of grating areas 22b, 23c provided with the X-ray shielding parts 22a, 23a of a first absorption type grating 22 and a second absorption type grating 23, X-ray transmission parts 22c, 23c are provided. The marker 11 attached to the subject H disposed between an X-ray source 12 and the first absorption type grating 22 is formed of a material having high X-ray absorptivity, and X-rays irradiated to the marker 11 pass through the X-ray transmission parts 22c, 23c without passing through the grating areas 22b, 23b of the first absorption type grating 22 and the second absorption type grating 23, and are detected by an FPD 21. Since a marker image detected by the FPD 21 is not intensity-modified by the first absorption type grating 22 and the second absorption type grating 23, it is accurately detected.