To improve the driving operability and the maintenance ability by stopping the pouring of compressed gas when the height of molten metal surface in a molten metal supplying vessel lowers to a prescribed height, stopping the supplying of molten metal into an injection sleeve and supplying a prescribed molten metal quantity into the injection sleeve.

The molten metal supplying vessel 20 is dipped into the molten metal M in a holding furnace 10 and the surface height of molten metal filled into the vessel, is detected with a molten metal surface height detecting instrument 30. Then, the molten metal supplying vessel 20 is held to the closed condition and the compressed gas is poured in the inner part thereof by using a compressed gas supplying device 40 to pressurize the molten metal. Thus, the molten metal in the molten metal supplying vessel 20 is supplied into the injection sleeve 4 through a molten metal supplying piping 50. The supply of the molten metal into the injection sleeve 4 is stopped by stopping the pouring of the compressed gas based on a signal of the molten metal surface height detecting instrument 30 in the vessel 20 by using a control device 60. By this method, the fixed quantity of the molten metal can automatically and efficiently be carried into the injection sleeve with a remote operation.