Provided is a peptide library. A peptide selected from items (1) and (2). A peptide selected from items (i) and (ii): (i) a peptide which contains the amino acid sequence represented by SEQ ID NO: 1 shown in the Sequence Listing and also contains an amino acid sequence encoded by a sequence lying between the 8th nucleotide and the 42nd nucleotide both located in the nucleotide sequence represented by SEQ ID NO: 14 shown in the Sequence Listing and an amino acid sequence encoded by a sequence lying between the 43rd nucleotide and the 93rd nucleotide both located in the nucleotide sequence represented by SEQ ID NO: 14 shown in the Sequence Listing adjacent to the amino terminal and the carboxyl terminal of the amino acid sequence represented by SEQ ID NO: 1, respectively； (ii) a peptide which has an amino acid sequence that is produced by substituting one to five amino acid residues other than an amino acid residue Xaa, which are located in a sequence lying between the 1st amino acid residue and the 12th amino acid residue as numbered from the amino terminal in the amino acid sequence represented by SEQ ID NO: 1 contained in the amino acid sequence for the peptide (i), by a conservative amino acid residue or conservative amino acid residues, deleting the one to five amino acid residues, adding a conservative amino acid residue or conservative amino acid residues to the one to five amino acid residues or inserting a conservative amino acid residue or conservative amino acid residues into the one to five amino acid residues.
