We proposed a protein detection system using two peptides; molecular recognition peptide and quenching peptide incorporating tryptophan. IgG was used as the model protein and the Atto655-labeled NKFRGKYK was selected as the probe for recognition of IgG. The quenching peptide, WWWG-DIAVEWES, was newly designed using a peptide array, and showed effective quenching of Atto655-labeled NKFRGKYK within 30 s. The quenching effect decreased in the presence of IgG, and IgG was detected above 10 nM.