The major purpose of this study was analyzing of farmer’s intention in related to organic agriculture by using of the Theory of Planned Behavior (TPB). Farmers of Chungchung Province (n=164) were administered a questionnaire survey that measured TPB constructs. The data and hypotheses were analyzed using multiple regression and confirmatory factor analysis by SPSS 21.0 and AMOS 21.0. Results showed that attitude, subjective norms, and perceived behavior of control were all positively related to farmer’s intention of organic agriculture and explained power of the model was relatively high which was 51 percent. Also the results of the analysis showed that the subjective norm was a key dimension of farmer’s intention in terms of standardized coefficient. The study demonstrated that the reduced theory of planned behavior was fit for factors of farmer’s intention. The meaning of the study and implications for future studies were discussed.