To improve the efficiency of melting heat while restraining the oxidation of a raw material by charging the raw material containing turning chips under a state, in which a molten metal exists by previously melting the metal in a rotary furnace rotating around the center axis of a cylindrical furnace body as the horizontal direction.

The furnace body 2 composed of the cylindrical body lined with a refractory 1, is rotatably supported with supporting rollers 3 by keeping the center axis of the cylindrical body in the horizontal direction and is rotated at a prescribed rotation speed by using a motor 4 as a driving source. At the one end side of the furnace body 2, a burner hole 5 and a molten metal tapping hole 6 are arranged and, at the other side, a gas exhaust hole 7 is arranged and the metal in the furnace body 2 is melted with an oxygen burner 8. In this constitution, when the metallic raw material containing ≥25 wt.%, desirably ≥50 wt.% turning chips is charged and melted, its molten metal is previously made to exist in the furnace body 2. In this way, the turning chips which have not received such pretreatments as removal of oil content, pressing, and the like, can efficiently be melted.