Introduction Psychological factors such as anxiety and confidence that students have in the patient care situation are important in that this affects the actual clinical performance. Students who are just starting clinical practice have a lack of clinical knowledge, skill proficiency, and patient communication skills, so they experience anxiety and lack of confidence in clinical setting. Practice in a safe environment, such as simulation education, can help students perform more settled and competently in patient care. The purpose of this study was to analyze the effect of high-fidelity simulation experience on anxiety and confidence in medical students. Materials and methods This study enrolled 37 5th-year students at Ajou University School of Medicine in 2020. Two simulation trainings were implemented, and a survey was conducted to measure students' level of anxiety and confidence before and after each simulation. Based on the research data, a paired t-test was conducted to compare these variables before and after the simulation, and whether this was their first or second simulation experience. Results Students had a significantly lower level of anxiety and a significantly higher level of confidence after the simulation than before. In addition, after one simulation experience, students had less anxiety and more confidence before the second simulation compared to those without simulation experience. Conclusions We confirmed that medical students need to be repeatedly exposed to simulation education experiences in order to have a sense of psychological stability and to competently deliver medical treatment in a clinical setting. There is a practical limitation in that medical students do not have enough opportunities to meet the patients during clinical practice in hospitals. Therefore, in order to produce excellent doctors, students should have the expanded opportunities to experience simulation education so they can experience real-world medical conditions.