When collecting samples of tobacco leaves before separating the stems and drying, at the Denchai Redrying Plant, was found that spraying denitrifying bacteria was able to decrease degradation ratio of TSNAs by 60.00%. The total TSNAs denitrifying bacteria lower than the control which were significant from total TSNAs control at 0.50 ppm to 0.20 ppm of denitrifying bacteria also reduced the NNN NNK and NAT in the tobacco leaves too.