A novel immobilization method of blue copper protein azurin on a gold surface was developed without a chemical linker using recombinant technique. Azurin was recombined with a cysteine anchors by site-directed mutagenesis (SDM) and used to effect the mutations, changing the codon for Leu39Cys (L39C) from CTG to TGC. The immobilization of the functionalized protein is confirmed by surface plasmon resonance (SPR) and its surface morphology is analyzed by scanning tunneling microscopy (STM). The immobilization efficiency has been increased about 76.3%, as compared to that of wild type azurin. The electrochemical property of the fabricated thin film was investigated by cyclic voltammetry (CV). As a result, cysteine-modified azurin can be used for making high quality protein film, and applied to the fabrication of nano-scale bioelectronics.