Purpose: This study aimed to examine the effect of tabletop disaster simulation of nursing students’ disaster preparedness and core competencies on disaster nursing. Methods: This study employed a nonequivalent control group multiple time-series design. The experimental group (n=27) underwent a lecture and nursing simulation education program on disaster nursing. Control group (n=27) underwent only lecture a review on disaster nursing. Data were analyzed by using descriptive statistics and repeated ANOVA and Bonferni test. Results: Disaster preparedness showed significant differences in groups by time (F=47.25, p<.001). Competencies on disaster nursing showed significant differences in groups by time (F=19.38, p<.001). Conclusion: This study showed that disaster nursing tabletop simulation education program was significantly effective in increasing disaster preparedness and core competencies on disaster nursing in nursing students.