The present invention pertains to a polycrystalline membrane containing metal nitride particles represented by the general formula MNx (where M is a metal element in which the Fermi energy is in a position higher than −4.4 eV vs L.V. and x is the range over which a rock salt-type structure can be assumed), in which the crystallite size determined by transmission electron microscopy is 10 nm or less, at least some of the crystallites have rock salt-type structure, and the crystallites exhibit (111) orientation but substantially do not exhibit (100) orientation. The present invention also pertains to a method for manufacturing a polycrystalline membrane, comprising forming, by sputtering, a polycrystalline membrane on a substrate having a temperature of less than 200° C., the polycrystalline membrane being represented by the general formula MNx and being such that at least some crystallites have a rock salt structure and the crystallites exhibit (111) orientation but essentially do not exhibit (100) orientation. The present invention provides a hydrogen-permeable TiNx microparticle membrane exhibiting a higher mixed hydride ion (H−)-electron conduction.