To provide a method for manufacturing a device such as a diffraction optical device having good optical performance and high accuracy by which the optical substrate is prevented from etching due to overetching of a hard mask, and to provide a method for manufacturing an optical system, a projection exposure device, a semiconductor device or the like having the above diffraction optical device.

The method of manufacturing a device having a multilevel step pattern includes a process of forming a hard mask pattern on the substrate by etching and forming the multilevel step pattern by using the obtained pattern as the reference. When the hard mask pattern is formed, an etching stopper layer is formed between the material layer for the hard mask and the substrate and then the material layer is etched.