Provided is a cyclic peptide, which is represented by Formula (I) or Formula (I') and has excellent antibody binding properties and improved chemical resistance, an affinity chromatography support, a labeled antibody, an antibody drug conjugate, and a pharmaceutical preparation. €ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒR N -X g -[X i -X a -X m -X 1 -X 2 -X 3 -X n -X b -X j ] k -X h -R C ···€ƒ€ƒ€ƒ€ƒ€ƒ(I) In Formula (I), X a and X b each independently represent an amino acid residue derived from an amino acid, other than L-cysteine and D-cysteine, having a thiol group on a side chain and are bonded to each other through a disulfide bond, or, one of X a and X b represents an amino acid residue derived from an amino acid, other than L-cysteine and D-cysteine, having a thiol group on a side chain and the other represents an amino acid residue derived from an amino acid having a haloacetyl group on a side chain, and X a and X b are bonded to each other through a thioether bond. €ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒR N -X g -[X i -X a -X m -X 1 -X 2 -X 3 -X n -X b -X j ] k -X h -R C ···€ƒ€ƒ€ƒ€ƒ€ƒ(I') In Formula (I'), one of X a and X b represents an amino acid residue derived from L-cysteine or D-cysteine and the other represents an amino acid residue derived from an amino acid having a haloacetyl group on a side chain, and X a and X b are bonded to each other through a thioether bond, or, one of X a and X b represents an amino acid residue derived from L-penicillamine or D-penicillamine and the other represents an amino acid residue derived from an amino acid having a haloacetyl group on a side chain, and X a and X b are bonded to each other through a thioether bond.
