To prevent noise due to a marker indicating the position of a subject when capturing a phase contrast image using a fringe scanning method.

A subject H to which a marker 11 is attached is arranged between an X-ray source and an FPD 21. On the basis of a distance L4 in a z direction from an X-ray focus 12a to the edge part Ha of the subject H, a distance L5 in the z direction from the X-ray focus 12a to the edge part 11a of the marker 11, a distance L6 in the z direction from the edge part 11a of the marker 11 to the FPD 21, a distance T1 in an x direction from one end of the X-ray focus 12a to the edge part Ha of the subject H, and the width w of the X-ray focus 12a, a distance T for preventing the image of the subject H detected by the FPD 21 and the image of the marker 11 from overlapping is calculated, and the position of the marker 11 is adjusted such that an interval between the edge part Ha of the subject H and the edge part 11a of the marker 11 is equal to or longer than the distance T.