To provide a method for molding capable of forming an air gap having a small inlet continuously perforated therein from the surfaces of a concrete and a porous concrete and having a wide inside in an arbitrary shape.

The method for manufacturing the perforated concrete product by a solid material originated from a starch comprises the steps of reforming the starch or a vegetative substance containing the starch by heating in the presence of water, and forming various type solid shape materials by utilizing the fact that the substance is solidified by a drying step and hence hardly redissolved in water. The method further comprises the steps of stationarily disposing the solid shaped material in a form so that a small-diameter part is brought into contact with the form before the concrete is placed and solidified, filling and solidifying the concrete, removing the solid shaped material by pressurizing warm water after the material is released from the form, and molding the perforated concrete and the porous concrete having a small inlet and air gaps of wide arbitrary shape continuously perforated therein and having small inlet.