To provide a method for manufacturing a multi-surface reflection mirror having a reflection plane shape with a high yield, and further to obtain a semiconductor aligner with higher throughput.

The method for manufacturing the multi-surface reflection mirror comprises repeatedly arranging a basic reflection plane, forming a part of a specified curved surface into a plane shape, on an arrangement table and consists of a first positioning part forming step to form the first positioning part on the basic reflection plane and a second positioning part forming step to form the second positioning part on the arrangement table and a contacting step to contact the first positioning part against the second positioning part.