The purpose of this study is to forecast a behavior model of Jeju convention participant as verifying whether the facts, suggested in the Theory of Planned Behavior by Ajzen, such as attitude toward the behavior, subjective norm, and perceived control, affect singnificantly the intentional behavior of Jeju Island convention participants. The difference between a first visitor and a return visitor to Jeju island are examined. Research indicates that the subject`s behavioral intention is affected by attitude toward the behavior and perceived behavioral control. The subjective norm doesn`t affect significantly the behavioral intention. There was no apparent significant difference between a first visitor and return visitor to Jeju island in terms of the three factors and relation with behavioral intention. Through this research, it is shown that the Theory of Planned Behavior is a very useful model to forecast the participation behavior of convention participants and surrounding pressure or opinion, visit experience are not the main fact for the participation behavior. Base on this study, further investigation is required.