BACKGROUND: Advocates for victims of sexual assault are exposed to the traumatic events of victims, which can lead to occupational stress. Occupational stress specific to advocates who support victims can cause compassion fatigue and burnout, which can worsen their mental health. Furthermore, such exposure could lead to compassion satisfaction, which, in turn, may buffer compassion fatigue and burnout. To improve the mental health of advocates for victims of sexual assault in Japan, this study aimed to evaluate a hypothesized model explaining the effect of occupational stress on their mental health. METHODS: This cross-sectional study was conducted using a self-administered questionnaire via mail. The sample comprised 560 advocates from one-stop support centers for victims of sexual assault. Questionnaires comprising the components of the hypothesized model, namely, compassion fatigue, burnout, compassion satisfaction, traumatic stress symptoms, and psychological distress, were mailed. After using descriptive statistics, a path analysis was conducted to test the hypotheses and the fitness of the model. RESULTS: Data from 250 participants were analyzed. The prevalence rates of compassion fatigue, burnout, and compassion satisfaction were 30%, 65%, and 4%, respectively. The hypothesized model demonstrated a good fit. Compassion fatigue exerted a significant positive effect on traumatic stress symptoms and psychological distress. Burnout also demonstrated a significant positive effect on psychological distress. However, its association with traumatic stress symptoms was not significant. Compassion satisfaction exerted a significant negative effect on compassion fatigue and burnout. CONCLUSIONS: Improving the mental health of advocates, particularly for traumatic stress symptoms, requires not only intervening in burnout but also improving compassion fatigue. Increasing compassion satisfaction contributes to the improvement of compassion fatigue and burnout. Therefore, creating a supportive environment that considered these would help improve the mental health of the advocates.