To continuously and stably obtain a high quality cast product without cast defect by providing an introducing tube incorporated into a ladle at the one end and inserted into an injection sleeve while projecting from the ladle at the other end to pour molten metal into the injection sleeve.

The empty ladle 20 is incorporated into a melting and holding furnace 10, and the ladle 20 is stood still so that the lower surface of a closed cover 20b corresponds to the molten metal surface level in the melting and holding furnace. A valve rod 22 is risen by operating a valve rod cylinder 24, and a suction hole 20c is made to opening state, and while exhausting gas in the ladle 20, the molten metal M in the melting and holding furnace 10 is naturally sucked into the ladle 20. Successively, after completing the fill-up of the molten metal into the ladle 20, the suction hole 20c is closed and the tip part 28a of spouting part of the introducing tube 28 is lowered and adjusted so as to approach the upper surface of a plunger chip 200a and inert gas pressed to the low pressure is poured into the ladle 20. The molten metal surface in the ladle 20 is pressed and the molten metal is flowed in the introducing tube 28 and dropped from the tip part 28a of spouting part of the introducing tube 28 and started to pour into the injection sleeve 200.