In fabricating an X-ray mask, a chromium oxide film serving as an etching stopper is formed on a diamond film serving as an X-ray transmitter. Then, a diamond layer serving as a first X-ray absorber is formed on the chromium oxide film. Thereafter, a tungsten layer serving as a second X-ray absorber is formed on the diamond layer. Consequently, the diamond layer and the tungsten layer form an X-ray absorber having a laminated structure. When the X-ray absorber has a laminated structure including substances having different compositions, the transmittance and the phase shift quantity of the overall X-ray absorber can be readily adjusted. Thus, a method of fabricating an X-ray mask providing improved resolution of the pattern of a semiconductor device or the like is obtained.