The thick type sensor having Pt/Na super ionic conductor(NASICON) Pt/Na2SO4/Pt catalyst system for SO2 gas sensing was fabricated by screen printing method. The phases of NASICON with the variation of sintering temperature (1050 degreesC, 1150 degreesC, 1250 degreesC) and sintering time (1.5hr, 2.5hr, 3.5hr) were investigated by XRD. The variation of electromotive force of the sensor with SO2 concentration and operation temperature were also investigated. The major phase of NASICON film sintered at 1150 degreesC for 3.5hr was sodium zirconium silicon phosphate (Na3Zr2Si2PO12). The Nernest's slope of NASICON sensor for SO2 gas with the variation of concentration from 10 to 100 ppm was 176.12 mV/decade at the operating temperature of 500 degreesC. The increase of oxygen partial pressure was not affected to the variation of Nernst's slope.