Purpose: The purpose of this study was to identify the effects of secondary traumatic stress and compassion satisfaction on burnout in psychiatric nurses and the moderating effects of social support. Methods: The participants were 214 psychiatric nurses from G city & C, G, J province. Data were collected from October 23 to November 6, 2015 and analyzed using t-test, ANOVA, Pearson correlation coefficients, multiple regression analysis and moderated regression analysis. Results: Secondary traumatic stress and compassion satisfaction had significant influence on burnout in psychiatric nurses. The explained variance for burnout was 67%. However, social support did not moderate the effect of secondary traumatic stress and compassion satisfaction on burnout. Conclusion: Findings indicate that burnout in psychiatric nurses may have a direct influence on their nursing services. There is a need to provide nursing intervention programs in order to prevent and alleviate burnout in psychiatric nurses by decreasing secondary traumatic stress and increasing compassion satisfaction.