and stored a pressurization mechanism 23 that pressurizes the foamed sand s within the sand tank 22 and a packing port 24 that connects the sand tank 22 to the cavity c of the metallic mold 2 the sand tank 22 is set onto the metallic mold 2 upon closing and clamping the stationary mold 12 and the movable mold 13 and by pressurizing the foamed sand s within the sand tank 22 by the pressurization mechanism 23 the foamed sand s is packed into the cavity c of the metallic mold 2 through the packing port 24 the mold clamping device 4 includes a double acting air cylinder 26 that drives the movable base 15 an air source 27 that supplies compressed air to the air cylinder 26 a switching valve 28 that switches the supply of compressed air from the air source 27 to the air cylinder 26 to make the movable base 15 advance forward or retract backward a pressure adjusting valve 29 that adjusts the pressure of the compressed air to be supplied to the air cylinder a pressure gauge 30 that detects the pressure of the compressed air supplied to the air cylinder 26 and a control device 31 that controls the operation of the switching valve 28 and the pressure adjusting valve 29 the control device 31 controls the switching valve 28 to switch the supply of compressed air so as to elongate retract an activation rod 26 a.