Nicotine is a major component of tobacco alkaloids. Nicotine is synthesized via putrescine N-methyl transferase (PMT), quinolinate phosphoribosyl transferase (QPT) and nicotine synthase. In this study, we down regulated the QPT activity using RNAi technique. RNAi vector was constructed by amplifying 500 bp region of QPT and inserted to pFGJJ374 vector in forward and reverse directions. We transferred the vector to Agrobacterium tumefaciens (LBA4404) and transformed Nicotiana tabacum (NC82). The nicotine contents of the transformant were significantly decreased by the transformation. The QPT gene expression of the transformant was decreased to 1/40 - 1/218 of the control from the quantitative RT-PCR. We made homogeneous transformed lines by segregation of the transformants. The low nicotine contents of the homogeneous lines were steadily maintained over the generations. The transformed lines could be used for low nicotine cigarette manufacturing.