PROBLEM TO BE SOLVED: To provide a peptide which can highly selectively adsorb IgG type antibodies with high adsorption capacity.SOLUTION: The invention provides a body fluid purification device comprising a peptide of a certain specific amino acid sequence having a helix loop helical structure, an adsorbent for IgG antibodies immobilized to a water-insoluble carrier using the peptide as a ligand to allow the IgG antibodies to bind, an IgG antibody adsorber filled up with the adsorbent, and the adsorber.