PURPOSE: To improve the yield of a molten steel and to enable repetitive use of refractories for charging in in the stage of casting the molten steel by a bottom running ingot casting method into a casting mold by blowing inert gas with high pressure into the refractories for charging thereby eliminating the remaining molten metal in the refractories for charging.

CONSTITUTION: The molten steel in a ladle 19 is bottom-cast into a casting mold 16 through a nozzle 18 and a charging pipe 10 formed of refractories. A sealing damper θ is inserted by a hydraulic device into a space 21 sealing the bottom of the ladle and the pipe 10 upon ending of casting into the mold 16 and thereafter inert gas such as Ar is forced into the pipe 10 from a force feeder 20. The remaining molten steel in the pipe 10 is charged as a part of a casting into the mold 16, by which the yield of the molten steel is improved. Since the inside of the pipe 10 is emptied, said pipe is usable again as a charging pipe for bottom casting.