Samsung conglomerate typically has central controlling shareholders and family-related companies to control 63 related companies. This study introduces centrality index utilized in Social Network Analysis (SNA) to measure the changes in significances of controlling shareholders after the merger between Samsung C&T and Cheil Industries. Empirical results are as follows. The first, the out-degree centrality, closeness centrality, betweenness centrality of Samsung C&T have significantly increased after merger between Samsung C&T and Cheil Industries. The Second, the eigenvector centrality of Lee Jae-Yong has significantly grown up to that of Lee Gun-Hee after merger between Samsung C&T and Cheil Industries. This result shows that the controlling power of Lee Jae-Yong has strengthen through the business combination between related companies. The third, the results of modularity test specially indicates that the community of Samsung Electronics has transferred from Lee Gun-Hee’s to Lee Jae-Yong’s after the merger between Samsung C&T and Cheil Industries. Finally, the degree centrality of Samsung Biologics (deeply doubtful with the issue of accounting fraud) has gradually grown up. Furthermore, Samsung Biologics has strongly connected with the highest-ranked degree centrality companies such as Samsung Electronics and Samsung C&T. This study provides the implications about the impacts of the merger between related companies on the changes in centralities of Samsung conglomerate’s controlling shareholders based on the social network analysis. We can expect the expanded corporate governance-related researches utilizing the SNA.