PURPOSE: To enable ingot making of extremely low nitrogen steel of high quality by injecting inert gas into inner part in a mold to substitute air with inert gas, fitting metal foil on upper face of the mold to make there shutting-off condition from the air and casting molten metal with bottom pouring.

CONSTITUTION: The mold 1 is set on a double surface plate 3 on upper surface of the surface plate 2 arranging a runner 4. The molten metal from a melting furnace is cast into this mold 1 from the bottom part through a ladle 7 and a nozzle at the bottom face thereof and sprue 6, pouring tube 5 and the above runner 4 to make a steel ingot. In the above bottom pouring ingot making method, the inert gas is injected into the inner part in the mold 1 and the air in the inner part, desirably together with the air in inner parts of the sprue 6, pouring tube 5, runner 4, etc., is substituted with the inert gas. Then, before or after substituting the inner part as the above, the metal foil 9 of Al, etc., is fitted on the upper face of mold 1 through a feeder head mold 8. After making the inner part of mold 1 under condition of shutting off from the outer air with this way, the molten metal is cast. By this method, without getting nitrogen in the air into the steel ingot, and while preventing mingling of waste brick, etc., the extremely low nitrogen steel having high quality can be obtd.