Abstract: Gas manifolds which are excellent in both phosphoric acid proof and electric insulation and which have sufficient corrosion proof over a long period are provided. A resin sheet with high phosphoric acid proof is folded to have a size smaller than that of the corner sections of the inner plane of gas manifolds by the size corresponding to a thermal expansion, and the folded planes are thermally compressed in air tight to form box-shaped linings. These linings are applied to the inner planes of the gas manifolds. Patches are thermally compressed to the outer surface of the bottom section of the linings and each patch is fitted loosely with a male hook or a female hook. A female hook or a male hook for engaging with the hook on each patch is fitted on the inner plane of the gas manifolds at an opposing position. The linings can be fixed to the gas manifolds engageably and disengageably by these hooks.