Abstract: Alignment in X-ray lithography is generally effected in such a manner that the surface of a target mark for alignment formed on a wafer is illuminated with light for alignment through an X-ray mask, and the position of the wafer is detected from the reflected light. On the basis of the finding that the reflected light from the mask, particularly from an absorber formed thereon, greatly degrades the precision and reliability in measurement, the present invention provides a pattern transfer mask provided with a thin film which lowers the reflection factor of the mask the thin film having a thickness set a .lambda./4n (.lambda.:the wavelength of the light for alignment; n: an integer) or an odd-number multiple thereof. Thus, it is advantageously possible to overcome the above-described lowering of precision and reliablity.