By steps of forming first masks 13, 14 each having a first pattern on a first surface of a substrate 11 on which a membrane is to be formed, etching the first surface of the substrate 11 by using the first masks 13, 14 to forming first support beams 15, positioning a second surface of the substrate 11 on the basis of the first pattern on the first surface, forming a second mask 17 having a second pattern on the second surface of the substrate 11 based on the alignment and etching the second surface of the substrate 11 in dry by using the second mask 17 to form the second support beams 20, a membrane member 22a where the first and second support beams 15, 20 are formed on both surfaces of the membrane 12 is manufactured. Consequently, it is possible to provide the membrane member that is sufficient in strength and is hard to be deformed by heat.