A protein chip of a S-L-SP form wherein a substrate peptide (SP) is immobilized on a solid substrate (S) by the mediation of a linker protein (L). Such chip is usefully employed in a method for analyzing the interaction between a reactive protein and its substrate peptide involving the steps of: adding to the protein chip a reactive protein showing a specific interaction with the substrate protein immobilized on the protein chip; and detecting the interaction between the reactive protein and the substrate peptide. The use of such protein chip and methodology allows an increase in the reactivity between a peptide with low molecular weight and an enzyme with high molecular weight and between the peptide and a reactive antibody on the protein chip, so that the interaction between the peptide and the protein can be analyzed rapidly and massively.