PURPOSE: To surely prevent inner continuous parts from separating from and peeling off each other by a method wherein inorganic fibers are piled up on a first filtering face, which locates at the surfaces of the inner continuous parts of a molding, an on a second filtering face, which corresponds to the outer surface shape, by sucking solvent through the suction ports of an outer mold so as to constitute an outer wall integrally.

CONSTITUTION: Inner continuous parts such as partition wall and the like are formed by piling up inorganic fibers on the outer peripheral surface of a first filtering face 21. A second filtering face 22 is formed in connection with the first filtering face 21 and corresponds to the outer surface shape of a silencer. By forming the first filtering face 21 and the second filtering face 22 on a filtering medium 20, filtering spaces 24, into which slurry is introduced, are formed in the interior of the medium 20. The filtering medium 20 is fixed into an outer mold 30 so as to be made into an integral body together with the outer mold 30 in order to efficiently manufacture a molding, which is mainly made of inorganic fibers. By driving a sucking device 36 under the condition that the outer mold 30, in the interior of which the filtering medium 20 is supported and fixed, is immersed in the slurry, in which fibrillated inorganic fibers are dispersed, inorganic fibers, which are piled up on the first filtering face 21 and on the second filtering face 22, are taken out of the outer mold as a green molding and dried.