NO reduction mechanism of Cu-electroplated activated carbon fibers (ACFs) has been studied. The surface properties of ACFs were determined by XPS analysis and their microstructures were investigated by XRD measurements. The specific surface area and micropore volume of ACFs were studied by BET and t-plot methods in $N_2$/77K adsorption isotherms, respectively. And, NO removal efficiency was confirmed by a gas chromatographic technique. The copper metal supported on ACFs appeared to result in an increase in NO removal, in spite of the decrease in the specific surface area or micropore volume of the ACFs. Consequently, the presence of Cu on ACFs played an important role in enhancing the reduction of NO to form Cu$_2$O and $N_2$, which was mainly carried out by the catalytic reactions of C-NO-Cu.