Soil biofiltration is an environmentally-sound technology for elimination of VOCs, odorous and NOx compounds from a low concentration, high volume waste gas streams because of its simplicity and cost-effectiveness. This study was performed to evaluate effect of removal of gaseous NOx using a soil and a yellow soil. Over 60% and 48% of NOx from a soil and a yellow soil was removed at the inlet NO concentrations of 423~ 451ppb, respectively. The bio-filter using a soil media was capable of purifying NOx with a different natural processes. Although some of the processes are quite complex, they can broadly be summarized as adsorption into soil pore water, and biochemical transformations by soil bacteria. When the filteration bio-reactor was applied to a soil and a yellow soil, effective NOx removal was obtained for several times and months. These results show that a soil biofilter can be of use as an alternative advanced NOx treatment system.