Multi-walled and single-walled carbon nanotubes were synthesized on platinum plate (MWCNTs/pt) and gold wire (SWCNTs/Au) electrodes, respectively, using a chemical vapor deposition (CVD) method. These carbon nanotube-modified electrodes were immersed into solutions of glucose oxidase (GOX) and D-fructose dehydrogenase (FDH) to immobilize these enzymes onto the electrode surfaces. After GOX was immobilized onto the MWCNT/Pt electrode, the well-defined catalytic oxidation current was increased from ca. -0.45 V (vs. Ag/AgCl/saturated KCl), which was close to the redox potential of flavin adenine dinucleotide as a prosthetic group of GOX under physiological pH values. Furthermore, catalytic oxidation currents of fructose based on direct heterogeneous electron transfer reactions between FDH and the SWCNT/Pt electrode were observed.