This study demonstrates the measurement and analysis of interfacial reactions of metal ions with organic ligands using the time-resolved SPR instrument. For the substrate, an HDT (1,6-hexanedithiol) ligand was immobilized on a gold thin film using the SAM method. The 50-nm-thick gold thin film was fabricated by thermal evaporation. The target metal ions were Pt ions in an aqueous solution. The adsorption kinetics of metal ions to HDT ligands was obtained.