PURPOSE: To incorporate additives into a molten metal without splashing by continuously charging the additives through a feed port into the molten metal in an enclosed pressure atmosphere higher than the atm. pressure so as to be intruded into the negative pressure of the high-velocity gaseous flow in the direction crossing the charge direction and blowing such additives into the molten metal.

CONSTITUTION: The molten metal 2 in a transfer rounder 1 of which the inside surface is covered by a refractory material 4a and a cap body 5 is prevented form solidifying or from solidifying and oxidizing by combustion gases 8, 10 blown from burners 6a, 6b. The granular particle additives 13 continuously supplied at a specified rate by a water cooling conveyor 14 are charged from the feed port 12 and are intruded into the negative pressure by the Venturi effect of combustion gaseous flow 10. Such aditives are blown to the surface of the molten metal 2 by which the additives are incorporated into the molten metal 2. The granular particles 13 are thus substantially entirely incorporated into the atmosphere higher than the atm. pressure, by which the addition effect is made safe and sure. The crossing angle θ is adequately 45W55°.