This research presents an empirical study on UTAUT model in an ERP post-adoption environment, investigating the moderating effect of mid-level management support on the relationship between subjective norm, perceived behavior control and behavior intention. Using data gathered from ERP users in a large-scale enterprise, we showed that perceived usefulness, perceived ease of use, subjective norm, and perceived behavior control are critical cognitive beliefs influencing the behavior intention to use the ERP system. In addition, the hypothesis of moderating effect of mid-level management support has not been supported by strong empirical evidences. Theoretical implications and limitations are discussed.