To make a molecular assembly of cytochrome c onto the Au substrate, the cytochrome c was modified using the 2-succinimidyl-3-(2-pyridyldi-th-io)propionate(SPDP), so the functional group on the cytochrome c surface was modified. And the modified cytochrome c was adsorbed onto die Au substrate. The modified cytochrome c was examined by using UV-visible spectroscopy and FT-IR. Also, the morphology of cytochrome c adsorbed onto the Au substrate was analyzed by Atomic Force Microscopy(AFM).