Objective This study aimed to identify the factors affecting posttraumatic stress disorder (PTSD) symptom remission prospectively through a 1-year follow-up of sexual assault (SA) victims. Methods A total 65 female SA victims who visited the crisis intervention center were included. Self-administered questionnaires regarding PTSD symptoms and PTSD related prognostic factors were conducted at both recruitment (T1) and 1 year after recruitment (T2). The multivariate analyses were used to determine the significant predictors of PTSD remission/non-remission state 1 year after SA. Results In logistic regression analysis, both anxiety and secondary victimization were identified as significant factors explaining the results on PTSD remission/non-remission state at T2 (Beck’s Anxiety Inventory [BAI], p=0.003; Secondary Victimization Questionnaire, p=0.024). In a linear mixed analysis, both depression and anxiety were found to be significant variables leading to changes in Posttraumatic Diagnostic Scale for Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition from T1 to T2 (BAI, p<0.001; Center for Epidemiological Studies Depression Scale, p<0.001). Conclusion Depression, anxiety symptoms, and secondary victimization after SA were associated with PTSD symptom non-remission 1 year after SA.