Bt gene derived from the B. thuringiensis has been used for developing GM crops and those crops are already on the market. The aim of this study is to construct a genetic transformation with peppers using CryIAc1 gene and consequently to develop GM peppers resistant to the oriental tobacco budworm. We have developed transgenic peppers using Agrobacterium-mediated transformation, and obtained 5 T0 peppers. T0 peppers were self-crossed and T1 pepper fruits were exposed to larvae to test the survival rate. The survival rate of larvae that were fed with GM fruits decreased dramatically while with non-GM fruits the rate was not changed much. In order to establish the selection and the culturing of bug through a year, an incubating system for tobacco budworm in chamber was manufactured and a selection system under the media that are mixed with GM green pepper was obtained. Using those system, T3 peppers tolerant to tobacco budworm were selected.