The purpose of this study was to investigate the effects of dating violence on individuals with borderline personality tendency through complex posttraumatic stress. In particular, this study examined the moderated mediating effect of complex posttraumatic stress through resilience and social support on the influence of dating violence on borderline personality tendency. For this purpose, 436 unmarried women aged 20-39 years who had experiences of dating violence were measured and analyzed levels of dating violence, complex posttraumatic stress, borderline personality characteristics, resilience, and social support. The results of the analysis were as follows: First, a statistically significant relationship was shown between the variable of dating violence, borderline personality traits, and complex posttraumatic stress levels, and these showed a negative correlation with resilience and social support. Second, among the types of dating violence assessed, only emotional violence significantly predicted complex posttraumatic stress and borderline personality tendency. Third, the full mediation effect of complex posttraumatic stress was confirmed in the relationship between dating violence and borderline personality tendency. Fourth, there was no moderating effect of resilience and social support on the path from dating violence to complex posttraumatic stress. However, it was confirmed that the complex posttraumatic stress level that fully mediated the dating violence had a moderating effect on the borderline personality tendency. Fifth, as a result of verifying the moderated mediating effect, it was further confirmed that when the resilience and the social support levels were high, the effect of dating violence mediated by complex posttraumatic stress on the formation of borderline personality tendency was mitigated. Finally, this study suggested the implications for counseling and psychotherapy interventions for victims of dating violence in the future.