IgG-Fc binding peptide which functions as ligand for IgG purification was screened by peptide array. When sera from milk allergy patient were applied to the milk protein-explosive peptide array, some 16-mer binding peptides were found from both positive sera and negative sera. When cellulose membrane type peptide array was used for identification of binding peptide sequence, octamer peptide, LLRLKKYK, was found to strongly bind to mouse IgG. Since the octamer peptide weakly bound with IgA, it was suggested that the peptide is an IgG-Fc specific binding peptide. Furthermore, it was also suggested that the IgG-Fc binding peptide is available for purification of IgG-Fc.