Objectives: Suicide is the most frequent cause of death among Korean adolescents, and adolescents who have experienced trauma have an increased risk of post-traumatic stress disorder (PTSD) symptoms, depression, and suicide attempts. However, resilience and self-esteem are protective factors. We examined the effects of resilience and self-esteem on the relationship among traumatic experiences, PTSD symptoms, depression, and suicidal ideation. Methods: Middle-school students (n=403) completed questionnaires assessing traumatic experiences, PTSD symptoms, depression, suicidal ideation, resilience, and self-esteem. Path analysis was performed to investigate the mediating effects of PTSD symptoms, resilience, self-esteem, and depression on the relationship between trauma exposure and suicidal ideation. Results: Traumatic experience was positively correlated with PTSD symptoms, depression, and suicidal ideation. PTSD symptoms and depression were positively correlated with suicidal ideation. The relationship between traumatic experiences and suicidal ideation was mediated by PTSD symptoms, which had both direct and indirect effects on suicidal ideation; the indirect effect was mediated by resilience, self-esteem, and depression. Conclusion: Korean adolescents who had experienced trauma were more likely to develop PTSD symptoms, increasing their risk of depression and suicidal ideation. However, self-esteem and resilience may help protect against depression and suicidal ideation. Our findings could inform suicide prevention initiatives.