Provided is a method of selecting a polypeptide sequence which imparts a target substance binding-ability to a protein of interest, said method comprises repeating the following steps (1) to (3)(1) expressing a library of fusion proteins, each of which is composed of a random polypeptide and a protein of interest or part thereof, from a nucleic acid construct comprising a first nucleotide sequence encoding the random polypeptide and a second nucleotide sequence which is linked to the first nucleotide sequence in flame and encodes the protein of interest or part thereof,(2) contacting the library of fusion proteins with a target substance,(3) selecting a fusion protein which comprises a polypeptide sequence that binds to the target substance, and amplifying a nucleic acid construct which encodes the selected fusion protein.Further, provided is a peptide including the following amino acid sequence. Tyr-Xaa0-Xaa1-Tyr-Tyr-Xaa2-Xaa3-Tyr-Xaa4-Xaa5-Xaa6-Xaa7-Xaa8-Xaa9-Xaa10-Xaa11 (SEQ ID NO: Y: wherein Xaa0, Xaa1, Xaa2, Xaa3, Xaa4, Xaa5, Xaa6, Xaa7, Xaa8, Xaa9, Xaa10 and Xaa11 represent any amino acid) or Tyr-Asn-Asp-Tyr-Tyr-Tyr-Tyr-Cys-Tyr-Arg-Asp-Tyr-Asp.
