The electrochemical properties of immobilized Pseudomonas aeruginosa Azurin protein was investigated for its application to biomolecular electronic device. DTSSP (3,3-dithiobis(sulphosuccinimidyl propionate)) was used for the -thiol modification of Azurin Protein to immobilize a protein to gold electrode in order to enhance its orientation and immobilization capability. The redox characteristic influence of protein modification by DTSSP was investigated by UV spectroscopy. The effect of modification using DTSSP for the immobilization capability of protein was validated by surface plasmon resonance (SPR) spectroscopy and scanning tunneling microscopy (STM) investigation. The electrochemical results obtained by cyclic voltammetry (CV) showed that the well defined protein layer was formed on the gold electrode. This well ordered assembled Azurin on the target electrode can be used by the molecular size electronic device.