A target consisting essentially of a CoCrPt-based metal or a CoCrPtRu-based metal, and one or more metal oxides selected from the group consisting of SiO2, Cr2O3, CoO, TiO2 and Ta2O5, is heated in an upper crucible of a two-level crucible that includes the upper crucible with a through hole formed in a bottom surface, and a lower crucible disposed below the through hole. The target is heated at a temperature of from 1400 to 1790° C. if the target does not contain both TiO2 and Ta2O5. The target is heated at a temperature of from 1400 to 1630° C. if the target contains TiO2 but does not contain Ta2O5. The target is heated at a temperature of from 1400 to 1460° C. if the target contains Ta2O5. The metal thereby melted is caused to flow into the lower crucible, so that the metal is separated from the metal oxide.