This study attempts to analyze the antecedents of e-commerce user behavior and their effect on future purchase intentions. Theoretical exploration shows that the antecedents used in the behavior of e-commerce users are perceived self-efficacy, perceived ease of use and perceived usefulness. The study uses the behavior of e-commerce users as a mediating variable. The study was also conducted using a quantitative method, by distributing questionnaires to 250 e-commerce users in Indonesia. The analysis technique used is Structural Equation Modeling (SEM) with SmartPLS software. The results show that perceived self-efficacy had a positive effect on perceived ease of use and perceived usefulness. These three antecedents in turn have a positive and significant effect on future e-commerce shopping interest by using mediation of user behavior. The results are theoretically useful for deepening Technology Acceptance Model exploration by estimating future buying behavior and interest. Practically, this study encourages e-commerce platform website developers to increase the ease and usefulness to increase the positive behavior of users in purchasing products.