TECHNOLOGY FOCUS - CERAMICS AND GLASS - Preferred Properties: The porous base material is a porous ceramic having a hole diameter of 1-20 nm. The porous base material has a multilayered structure, with the uppermost layer having a hole diameter of 1-20 nm and the lowest layer having a hole diameter of 100 nm or more.    TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Property: The hydrogen-separation membrane has a hydrogen transmission rate of 1x 10-6 mol/m2.second.Pa or more. Preferred Conditions: The film-forming temperature is 400-700 degrees C. The chemical vapor deposition pressure-reduces another side of the porous base material during film-formation. The silica source lateral-pressure force of pressure of the other side of porous base material during pressure-reduction is below 1/100 with respect to 1 MPa from 100 KPa. The flow ratio of silica source is controlled during film-formation.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compounds: The silane having methoxy group(s) and bulky group(s) is of formula: H3CO-Si(-R2)(-R3)-R1, and the tetra-aryloxysilane is of formula: Si(-OR)4, preferably Si(-OAr)4, more preferably tetraphenoxysilane.R1-R3=methoxy, monocyclic hydrocarbon group, oxy monocyclic hydrocarbon group, condensed-ring hydrocarbon group, or oxy condensed-ring hydrocarbon group, with carbon atom(s) in oxy condensed-ring hydrocarbon group and monocyclic hydrocarbon group, and oxy monocyclic hydrocarbon group, condensed-ring hydrocarbon group, and oxy condensed-ring hydrocarbon group is group chosen from group substituted by nitrogen atom, oxygen atom, or sulfur atom;andR=group chosen from group in which carbon atom(s) in monocyclic hydrocarbon group and condensed-ring hydrocarbon group and monocyclic hydrocarbon group, and condensed-ring hydrocarbon group is group substituted by nitrogen atom, oxygen atom, or sulfur atom.R1-R3 are not methoxy simultaneously. Preferably, the silane having methoxy group(s) and bulky group(s) is phenyltrimethoxysilane or dimethoxydiphenylsilane.