The current body of literature in online brand community (OBC) area lacks of considering the most inherent characteristic of OBC: dynamics of OBC. Most previous studies assume OBCs a static object without adopting longitudinal views. Within an OBC, members interact with each other and their relationships wax and wane over time. The current study focuses the structural relationships among members within a community with adopting SNA (Social Network Analysis) approach. How they interact with each other and how their relationships evolve are investigated in terms of their postings on a main bulletin board. For a year and seven months, members of postings and their interacting relationships were analyzed. Major factors analyzed were the degree (of connectedness), Centrality, Centralization, and sub-network. With the result, the existing evaluative criteria including the number of members, postings and replies should have additional lenses with structural relationships among members by stages. Five stages of evolving were found and their specific characteristics were reported in the result. As an exploratory and descriptive study, several suggestions for following studies in this area and strategic implications for practitioners are yielded.