An object of the present invention is to provide a method for separating Dy and Tb from an alloy containing Dy and Tb as constitutional metals without using a solvent extraction method. The method of the present invention as a means for resolution is characterized by comprising vaporizing Dy by subjecting the alloy to a heat treatment in an atmosphere of a pressure Pt(Pa) that, when a Dy—Tb composition in the alloy is DyxTby (atomic composition ratio) and a heat treatment temperature is t, satisfies formula 1: PtTb