PURPOSE: To stably decarburize molten steel in a short time at high speed over a long period by blowing an inert gas into a vacuum vessel in a vacuum degassing furnace to disperse the molten steel into droplets, quenching the droplets through a cooling jacket provided on the peripheral wall of the vacuum vessel to separate the quenched droplets from the wall and remelting the droplets in the molten steel to decarburize the molten steel.

CONSTITUTION: A gas is blown into the molten steel 4a in a vacuum degassing furnace 2 from the gas blowing hole 9a in a vacuum furnace, the gas blowing hole 9b of an immersed pipe and the gas blowing hole 9c in the bottom of a ladle 1 to disperse a part of the molten steel in the vacuum vessel into droplets 6, and a part of the droplets are allowed to collide with the cooling jacket 10 provided on the peripheral wall of the furnace 2, deposited, quenched by the jacket 10, separated and remelted in the molten steel 4a. The molten steel 4a is dispersed into droplets by a series of operations, the degassing reaction proceeds from the surface of the droplet, the droplet is redropped into the molten steel or quenched by the jacket 10 surface, separated and redropped into the molten steel 4a, and the molten steel is recirculated without decreasing its yield.