An X-ray imaging system includes an X-ray imaging device and an image processing device including a reconstruction unit and an estimation unit. The X-ray imaging device uses a Talbot or Talbot-Lau interferometer including gratings disposed in a line. The X-ray imaging device obtains sets of moire fringe images by fringe scanning multiple times between which arrangement of the gratings is changed. In the fringe scanning, one of the gratings is moved relatively to the remaining grating. The reconstruction unit generates, on the basis of the sets, a reconstructed image which is a differential phase image, an X-ray absorption image and/or a small-angle scattering image. The estimation unit estimates, on the basis of the reconstructed image, a relative position of the moved grating from a reference position of the grating at each imaging in the fringe scanning.
