To develop a nicotine-degrading material (NDM), the natural herbal extract was studied. For the in vitro verification, the herbal extract was mixed into the dilute nicotine solution and the ability of NDM to degrade nicotine into cotinine was measured spectrophotometically. In the in vivo study, the rats in experimental and control groups were orally fed with the herbal extract and water, respectively, for 2 weeks. And then, 3 ㎎/㎏ nicotine was administered to both groups by intraperitoneal injection. In results, the ability of NDM to degrade nicotine into cotinine was shown 2.5 fold higher after 90 min reaction in comparison with the control group. In addition, a decrease of 33% in nicotine concentration and a increase of 57% in cotinine concentration were shown in rat blood. Therefore, NDM was shown to be effective in the conversion of nicotine into cotinine.