The Nuclear power plant (NPP) industries in Korea have been making efforts to reduce the human errors which largely contributed to 120 nuclear reactor trips from the year of 2001 to 2006. This study aims to develop a Crew Resource Management (CRM) training program that helps to improve plant performance by reducing the number of the reactor trips caused by the operators' errors. The CRM program was developed with focusing on nontechnical skills, such as leadership, situation awareness, teamwork, and communication, which have been widely known to be critical for improving the operational performance. In this study, the CRM program was applied to the operators performing simulation scenarios in the mockup of the main control room of the APR-1400. The CRM program was preceded with the lectures, emergency operation procedure scenarios designed by the process expert, task monitoring, and debriefings. Finally we verified the effectiveness of CRM training through the attitudes test and Behaviorally Anchored Rating Scale (BARS) to measure learning that has resulted from participation in the training program. The implication of the evaluation results was discussed in detail.