The sensitivity and the recovery behavior of SnO_2-based gas sensor prepared from a commercial SnO_2 powder were tested under the low concentration of DMMP(0.5μg/g) in the flow system at 350℃.In order to improve the sensitivity of the sensor,promoters such as NiO,Nb_2O_5,MoO_3,and Sb_2O_3 were added into SnO_2 powder.The sensitivities were increased up to 80% from 50% but they were not recovered.Only the SnO2-based gas sensor promoted with MoO_3 and Sb_2O_3 was recovered after detection of DMMP,although the recovery rate was slow.In particular,the SnO_2-based sensor promoted with 5wt% of MoO_3 and 1wt% of Sb_2O_3 simultaneously showed an complete recovery ability,though its sensitivity was 40% which was lower than that of SnO_2 gas sensor without promoters.This ability was discussed in terms of catalytic roles of promoters. The sensitivity and the recovery behavior of SnO_2-based gas sensor prepared from a commercial SnO_2 powder were tested under the low concentration of DMMP (0.5 μg / g) in the flow system at 350 ° C. In order to improve the sensitivity of the sensor, Promoters such as NiO, Nb 2 O 5, MoO 3, and Sb 2 O 3 were added into SnO 2 powder. The sensitivities were increased up to 80% from 50% but they were not recovered. Only the SnO 2-based gas sensor was promoted with MoO 3 and Sb 2 O 3 was recovered after detection of DMMP, although the recovery rate was slow.In particular, the SnO_2-based sensor promoted with 5wt% of MoO_3 and 1wt% of Sb_2O_3 shows an entire recovery ability, though its sensitivity was 40% which was lower than that of SnO_2 gas sensor without promoters.This ability was discussed in terms of catalytic roles of promoters.