An X-ray exposure system for exposing a semiconductor wafer to a mask with X-rays contained in synchrotron radiation, is disclosed. In this system, the mask and the wafer are held on a main frame so that their surfaces extend substantially parallel to a vertical axis. The main frame suspends from a supporting frame through a plurality of air mounts, each being vertically displaceable. The supporting frame is placed on the same reference surface as that of an SOR ring that produces synchrotron radiation. By using these air mounts, any tilt of the mask and the wafer relative to the irradiation region of the synchrotron radiation, as well as the position of the mask and the wafer in the vertical direction, with respect to the irradiation region, can be controlled and maintained constant. Thus, accurate pattern printing is ensured.