Although moral courage can play an important role in resolving some of the ethical dilemmas faced by clinical nurses, the concept of moral courage is in need of greater clarification. This study investigates some of the factors that influence moral courage, including moral sensitivity, ethical decision-making confidence, and ethical environment. A total of 148 nurses agreed to participate in an online survey for this study. The collected data were analyzed with Pearson’s correlation coefficient and multiple regression using the IBM SPSS 24 program. The analysis indicates that moral courage has a significant correlation with moral sensitivity (r=.55, p<.001), ethical decision-making confidence (r=.65, p<.001), and ethical environment (r=.66, p<.001). Ethical decision-making confidence and ethical environment were derived as factors that affect moral courage, and the explanatory power of these variables is 52.0% (F=20.94, p<.001). These findings justify the creation of ethical clinical environments in which nurses’ ethical decision-making confidence can be expressed as actual behavior. In addition, it is argued that ethical regulations and guidelines within clinical settings should be clarified in order to establish support systems that protect the well-being of patients and reflect the true value of professional nurses.