The major purpose of this study is to identify the factors influencing the implementation performance of ERP Systems from an integrated viewpoint. For this purpose, a research model is developed based on the literature reviews of ERP systems, contingency theory, and change management theory. The research model proposed fifteen variables as the factors influencing the implementation performance in the ERP systems. The data have been collected from the 164 enterprises which implemented ERP systems at least one year ago. The respondents were person in charge of ERP system of each corporation. The results of hypothesis testing through multiple regression analysis are summarized as follows. Firstly, standardization of work, concentration of decision making, top management concern and support, real user participation, project support goodness, ease of use, and system usefulness have positive influence upon non-financial performance. Secondly, market uncertainty, industrial competition, project support goodness, and customization minimization have positive influence upon financial performance. From the analysis, this research have identified important characteristics for the successful implementation of ERP systems. Consequently, this research ends with managerial and theoretical implications of the study results, as well as limitations and future research directions.