The purpose of the present study was to investigate the effects of indirect trauma on post-traumatic stress symptoms and to explore the vulnerability and resilience factors of posttraumatic stress disorder(PTSD). In order to achieve these goals, data from 100 employees who experienced frequent indirect trauma, whose main job involves visiting the scene of a traffic accident, were collected by utilizing the Posttraumatic Stress Diagnostic Scale, Impact of Event Scale, White Bear Suppression Inventory, Anxiety Sensitivity Index and Hardiness Scale. The analysis of the collected data produced the following results. First, it was found that the agents who are dispatched to the scene of an accident suffer severe PTSD, indicating that the group is vulnerable to PTSD. Second, anxiety sensitivity and thought suppression had partial mediation effects on the relationship between dispatch stress and PTSD, which suggests that each of the two factors may affect the severity of symptoms. Finally, it was observed that hardiness had a moderation effect on the relationship between dispatch stress and PTSD, implying that hardiness could act as a buffer in the stressful situation of having to visit an accident site. The present study significance lies to confirm the severity of the posttraumatic stress symptoms of the employees in the traffic accident site and suggest a new occupation group of indirect trauma. Furthermore, it suggested that thought suppression, anxiety sensitivity, and hardiness were psychological factors relevant to preventive interventions for trauma.