It is intended to provide a method of identifying a candidate for a drug which comprises measuring the concentration of a soluble peptide, oligopeptide, polypeptide or protein in an equilibrated state in a solvent in the presence of a test compound so that the peptide, oligopeptide, polypeptide or protein can be eliminated from a fibril or an aggregate. It is also intended to provide an elution promoter for eliminating a peptide, an oligopeptide, a polypeptide or a protein from a fibril or an aggregate which comprises a compound obtained by the above identification method as the active ingredient.