PURPOSE: To prevent the combustion of a molten metal and to suppress the decrease in the temp. of the molten metal in a communicating pipe by sealing a combustion-preventive gas into the hermetic space in the upper part of a storage vessel, contg. a casting cylinder and communicating pipe into the molten metal and communicating the same with cavities.

CONSTITUTION: The molten metal 20 of an Mg alloy, etc. is stored in the storage vessel 19 and the combustion-preventive gas such as SF5 is mixed at about 1% with air and is sealed into the hermetic space G in the upper part of the vessel to prevent the combustion of the molten metal 20. The molten metal 20 is cast through the casting cylinder 22, the communicating pipe 24 and a pouring port 5 into the cavities 14 when a pressurizing cylinder 26 is actuated to lower a pressurizing piston 28. The molten metal 20 in the pipe 24 is heated by the molten metal 20 enclosing the pipe 24, by which the temp. decrease is suppressed. The run in the cavities 14 is thus improved and the molten metal 20 is uniformly filled therein. A hydrostatic high pressure is exerted to the molten metal in the cavities 14 by the cylinder 26 in succession thereto to solidify the molten metal 20. The product having good quality without contg. air bubble is obtd. by such device.