Recently, many organizations are actively adopting Enterprise Architecture (EA) as a methodology to manage IT assets and build IT-based business system. However, most existing studies on EA have focused on the adoption stage of EA. Now the research concerning effective management and utilization of EA after adopting EA is keenly required. This study intended to empirically examine how the role of EA operating unit and the EA utilization capability of organizational members impact on EA performance at the post-adoption stage of EA. Based on Resource Based View (RBV), this study proposed the model and the hypotheses describing that the impact of the role of EA operating unit on EA performance is mediated by the EA utilization capability of organizational members. In order to test the hypotheses, the field survey whose respondents were seventy four Korean public agencies which have adopted EA was conducted by means of questionnaire. Data analysis was done with partial least square (PLS), which is a structural equation modeling (SEM) technique that uses a component-based approach to estimation. The results of the empirical analyses showed that the organizational operation ability of EA operating unit significantly influenced EA performance via the EA utilization capability of organizational members, but that EA education and training performed by EA operating unit did not. The results of this study provided a lot of theoretical and practical implications regarding EA management activities at the post-adoption stage of EA to enhance EA performance.