A cyclic peptide is proposed 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. rn-xg- [xi-xa-xm-x1-x2-x3-xn-xb-xj] k-xh-rc (i) in formula (i), each of xa and xb independently represents a residue amino acid derivative of an amino acid, other than 1-cysteine and d-cysteine, with a thiol group in a side chain, and both bond to each other via a bisulfide bond, or one of xa and xb represents a residue of amino acid derived from an amino acid, other than 1-cysteine and d-cysteine, with one thiol group in a side chain and the other represents an amino acid residue derived from an amino acid with a haloacetyl group in a side chain, and xa and xb bind each other through a thioether bond. rn-xg- [xi-xa-xm-x1-x2-x3-xn-xb-xj] k-xh-rc (i ') in formula (i'), one of xa and xb represents a residue of amino acid derived from 1-cysteine or d-cysteine and the other represents an amino acid residue derived from an amino acid with a haloacetyl group in a side chain, and xa and xb bond to each other via a thioether bond, or a of xa and xb represent an amino acid residue derived from 1-penicillamine or d-penicillamine and the other represents an amino acid residue derived from an amino acid with a haloacetyl group in a side chain, and xa and xb bond to each other through of a thioether bond.é proposto um peptídeo cíclico, o qual é representado pela fórmula (i) ou fórmula (i') e possui ótimas propriedades de ligação com anticorpo e resistência química aprimorada, um suporte para cromatografia de afinidade, um anticorpo marcado, um conjugado anticorpo-fármaco e um preparado farmacêutico. rn-xg-[xi-xa-xm-x1-x2-x3-xn-xb-xj]k-xh-rc ¿¿¿ (i) na fórmula (i), cada um de xa e xb representa independentemente um resíduo de aminoácido derivado de um aminoácido, que não l-cisteína e d-cisteína, com um gr
