PURPOSE: To produce a highly cleaned molten metal by providing plural filters having a different pore diameter, a filtration chamber having a partition wall and an inert gas injection means in a scrap melting furnace.

CONSTITUTION: Plural filters 6, 52, 53 and 54 having mutually different average pore diameter are arranged toward the downstream side in order of decreasing mesh, and hence the service life of the filters is prolonged. A partition wall is provided to form a filtration chamber on the downstream side of a scrap inserting and and melting chamber, and inert gas injection means 12 and 13 are furnished to the bottom and/or side wall of the chamber to degass the chamber or to remove an oxide film. Consequently, when the bubbles of the inert gas are floated up, gaseous hydrogen, etc., and oxide film in the melt are entrained by the bubbles to the melt surface, and the melt is agitated to remove the gaseous hydrogen, etc. The finer oxide film and inclusion are then removed by the filters.