The purpose of this research is to develop a comprehensive information system (IS) evaluation model for IS success linked to organizational performance. The primary focus of this research is to investigate the role of IT investment in business values by means of a group survey of about 300 business executives in Korea. We used the contingency theory to discover the mediation effect of IS investment on strategic alignment and IS success. In contrast to previous research, this study expanded the test scope to IS architecture and organizational structure at the operational level. The results from 273 business executives in Korea indicated that strategy integration with IT is positively related to IT investment, and IT investment is a critical antecedent of IS success. Thus, the implications of the findings are that right-directional IT investment has played an important role in the success of IT companies in Korea.