To obtain a dense molded article having high strength and to also simplify the structure of an apparatus.

In a molding apparatus 1 constituted so that a hydraulic inorg. molding material is introduced into the cavity formed by closing upper and lower molds 3, 2 under pressure and excessive moisture in the hydraulic inorg. molding material is sucked and removed from the water drain holes 21 bored in the mold surface of the lower mold 2 and the dehydrated molding material is molded into a desired shape, a hollow part 31 is provided to the part where the upper mold 3 enters the lower mold 2 by closing both molds and a pressure medium is introduced into the hollow part 31 under pressure to expand the wall 32 of the hollow part 31 toward the mold surface of the lower mold 2 to further compress the hydraulic inorg. molding material in the molds.