Incivility—including subtle put-downs, implicit discrimination, and aggressive attitudes—that pervades modern organizations has become a hidden cause of underperformance. This study focuses on the fact that incivility is not an indiscriminate act directed at random targets but rather a selective behavior reflecting power relations within organizations, and sought to comprehensively identify structural antecedents arising from dissimilarity among organizational members and social relationships, rather than the personal characteristics of perpetrators or victims. Accordingly, this study first predicted that demographic dissimilarity would generate exclusion and discrimination based on categorization and prejudice. Second, considering that incivility is a relational phenomenon resulting from interpersonal interactions, the study examined the effects of two representative network characteristics—centrality and ego-density—on members' perceptions of incivility. Third, the study sought to identify mechanisms that amplify or mitigate incivility by analyzing the interactions among these antecedents. To this end, data were collected from 225 employees belonging to two domestic companies, and research hypotheses were tested. The results showed that: 1) demographic dissimilarity increased incivility experiences, while centrality and ego-density decreased them; 2) interaction effects among structural antecedents were confirmed—specifically, centrality strengthened the positive effect of dissimilarity on incivility, while ego-density mitigated the effect of dissimilarity. Notably, when members with high demographic dissimilarity also had high centrality within the network, their perception of incivility increased, which is a meaningful finding. Based on these results, various theoretical and practical implications were discussed, and possible directions for future research were suggested.