Mixed-potential type sensors utilizing stabilized-zirconia (YSZ) and MNb2O6 (M: Co, Zn and Ni) sensing electrodes (SEs) were fabricated and examined for NO2 detection at high temperature. For mixed potential type NO2 sensor present fabricated, the device attached with CoNb2O6-SE has been found to give the highest response at 750℃compared with the other two devices and could detect even 0.1 ppm NO₂with an acceptable response value (5 mV). The present sensor showed fast response and recovery times to 100 ppm NO₂at 750℃, which are 3 s and 15 s, respectively. AV of the sensor attached with CoNb₂O₆-SE exhibited segmentally linear relationship to the logarithm of NO₂concentration in the ranges of 0.1-2 ppm and 2-300 ppm, which the sensitivities were 10 and 52 mV/decade, respectively. Moreover, the present device also displayed good repeatability, good wet resistance, slight drifts in 30 days high-temperature measured period, and excellent selectivity in the presence of various interfering gases at 750℃. Additionally, the mixed potential sensing mechanism was explained quantitatively and further demonstrated from the measurement of polarization curve.