A stencil mask includes a membrane forming thin layer having membrane areas and a border area that limits the membrane areas. The membrane areas have a plurality of pattern areas which include an aperture through which particle beams can permeate and non-pattern areas interposed between the pattern areas. A main strut supports the membrane areas and is formed on the border area of the membrane forming thin layer. An auxiliary strut is formed in the non-pattern areas inside the membrane pattern area such that the auxiliary strut divides the membrane areas into plural divided membrane areas. The auxiliary strut supports the divided membrane areas.