A cytochrome c onto photochemically patterned conducting sulfonated polyaniline (SPAN) was immobilized by using a self-assembly technique. The SPAN polymer was employed as a specific binding site for cytochrome c. The electrical conductivity of SPAN was allowed by doping of HCl. Physical and electrochemical properties of the self-assembled cytochrome c monolayer were investigated from the measurements of cyclic voltammetry and atomic force microscopy (AFM). Especially, the electrochemical activity of self-assembled cytochrome c immobilized on the SPAN with a high electrical conductivity was superior.