In this paper, we propose a scientific approach of redesigning organization to overcome subjective approaches previously used to redesign organizations. We introduce a new redesign approach using the Social Network Analysis(SNA) technique that is easy to analyze performance of organization and cooperative relationship. We show a case from A company in Steel industry to utilize the new approach to redesign organization. There are three levels of analysis using SNA that are personal level, group/team level and corporate level. In this case study, A company use analysis of group/team level. Diagnostic Tool is designed for redesigning A company's organization based on SNA. The result of analysis is very useful to the actual redesigning organization. Base on the theory of Social Network, cooperative relationship was investigated by frequency level that could be strong tie or weak tie. Density among more than 3 teams is used to find the flow information and work. The level of satisfaction about expected roles is used to evaluate team performance. We find that SNA makes it possible to redesign organization without qualitative approach in this study. And the result of SNA is useful for CEOs and executives to make right decision about organization redesign.