Deep X-ray Lithography (DXL), one of the microfabrication techniques using a synchrotron radiation, has been developed. To fabricate 3-D microstructures by DXL, a method was proposed that the relative position of an X-ray mask and a resist was changed. Thus, we calculated a shape of a 3-D microstructure fabricated by this method, based on deposited dose distributions on resist surface. In the calculation, we used the model in which an X-ray mask with a transmission area of a circular aperture was moving circularly during exposure. As a result, the calculated shape resembled the one fabricated by the exposure experiment.