To make it possible to prevent the external appearance failure of a molding due to clogging of a filter of the part opposed to a conduit.

The molding machine for a hydraulic inorganic molding comprises a male mold 2 and a female mold 3 which can be opened and closed in such a manner that many drain holes 11 are perforated at the surface of the mold 3, a conduit 5 opened with a mold cavity 4 formed at the mold 2 when the molds 2, 3 are closed, a hydraulic inorganic molding material supply tube 6 and a water supply 7 connected to the conduit 5 so as to be switched, and a filter 10 which can be extended into the mold cavity 4 upon closing and is suspended therein.