To provide a method for treating a metal, by which a metal can be enriched more safely or easier.

The method for treating a metal treats a metal of a metal-containing material that contains two kinds of metals of indium with a content rate (a) and tin with a content rate (b). The method for treating a metal includes: a temperature control step of heating the metal-containing material to melt the metal-containing material and cooling the molten metal-containing material at a cooling temperature controlled between a liquid phase temperature and a solid phase temperature; a centrifugal separation step of forming a solid material and a liquid material of the metal-containing material by means of the controlled temperature and separating the metal-containing material into the solid material and the liquid material by centrifugation; and a step of draining the liquid material separated by the centrifugation to obtain the solid material in which both of the content rate (a) of indium and the content rate (b) of tin are changed.