Disclosed is a melting furnace of metals and melting method thereof, which can control the rate at which a metallic raw material is introduced from a preheating section to a melting section within an optimum range and which can achieve efficient melting of the metallic raw material using oxygen burners only. The metal melting furnace has a melting section (22) provided with oxygen burners (21) and a preheating section (23) for preheating the metallic raw material located above the melting section, with a reduced section (24), having an inner diameter smaller than those of the melting section (22) and of the preheating section (23), being located between the melting section (22) and the preheating section (23).