The surface plasmon resonance (SPR) biosensor is a useful tool to analyze numerically the interaction of certain molecules. The most important advantage of the SPR assay as compared with other protein–protein binding assays is that it can calculate the affinity between protein and its binding partner, for this affinity is necessary to determine the priority of interactions between proteins. Although CCN proteins have been shown to have various binding partners, the affinities of many of them have not yet been determined. Therefore, it is important to determine the unknown affinities of known binding partners and to find new binding partners whose affinities need to be determined. This chapter provides helpful tips to use the instrument for determination of the affinities of binding between CCN proteins and their binding partners.