To obtain an opened porous sintered product without requiring a high cost by feeding a flowable mixture containing an aqueous polymer dispersion, a sinterable inorganic powder material and a dispersant into a precipitation bath for precipitating or coagulating the polymer to form a non-flowable product, subjecting the product to a discharging treatment, a drying treatment and a heating treatment to remove the polymer and the dispersant, and subsequently sintering the treated product.

The polymer is especially preferably styrene-butadiene copolymer or a polymer based on a 1-6C alkyl (meth)acrylate. The sinterable inorganic powder material is preferably a metal powder material, a mineral powder material, a ceramic powder material, a metal carbide powder material or a carbon nitride material. The dispersant is preferably ammonia, the ammonium salt of an organic or inorganic acid, or the tetraalkylammonium salt of a fatty acid. The precipitation bath is preferably the aqueous solution bath of an acid or salt. The feeding of the flowable mixture into the precipitation bath is carried out in the shape of liquid drops or extrusion molded products.