It is necessary to overcome the sensitivity for the further development and industrialization of impedimetric immunosensor. To improve the sensitivity of impedimetric immunosensor, we did systematic studies in the material science, surface chemistry, and electrochemistry together and a highly sensitive electrochemical platform for impedimetric immunosensors is proposed. To give a sufficient surface area for antibody immobilization, aluminum substrate was fabricated into nano-porous structure by anodization in 0.3% oxalic acid. In addition the optimal process to immobilize antibody onto aluminum surface using 3-aminopropyl triethoxy silane (APTES) was established. Anodization of aluminum at 40V in 0.3% oxalic acid provided a well-ordered nano-porous structure having an appropriate dimension in nano-pores for antibody immobilization. Evenly deposited APTES monolayer was observed when aluminum was silanized in 2.5% of APTES solution for 4 hrs. Through the fluorescent study of antibody immobilization on aluminum surface, we found that antibody was immobilized on nano-porous surface more 50% per unit area than on plain surface. Immunosensor constructed as the proposed optimal processes was sensitive enough to distinguish immunoreaction. The presence of 1µg/ml of staphylococcal enterotoxin B could be detected in less than 20 min with newly developed impedimetric immunosensor.