In this study, when cardiopulmonary resuscitation continued for a long time, the rescuer's blood lactic acid concentration, heart rate, and rating of perceived exertion were measured to identify the change in the rescuer's fatigue. Data collection was conducted from July 5 to July 9, 2021, with a total of 24 students, 12 students department of special warfare medical non-commissioned officer, and 12 students department of emergency medical technology at D University, undergoing a two-person alternative chest compression resuscitation for 60 minutes. As a result of the study, the rescuer's blood lactic acid concentration, heart rate, rating of perceived exertion, and chest compression speed were significantly changed according to the duration of CPR (p<.001, p<.001, p<.001, p<.001). blood lactic acid concentrations at every measurement cycle (30 minutes, 40 minutes, 50 minutes, 60 minutes) showed a significant positive correlation with heart rate (r=.696, p<.001, r=.672, p<.001, r=.709, p<.001, r=.782, p<.001), there was also a significant positive correlation with the rating of perceived exertion (r=.476, p<).05, r=.426, p<.05, r=.470, p<.05, r=.470, p<.05). Therefore, monitoring the fatigue of rescuers using heart rate and rating of perceived exertion will be useful for maintaining high-quality chest compression in situations where cardiopulmonary resuscitation is required for a long time.