In medical education, it is important for medical students to develop their ethics to respect patients' rights. Some physicians might make light of patients' rights, because the increased awareness of such rights might make it more difficult for them to conduct medical practice. In the present study, predictors significantly associated with “a sense of resistance to patients' rights” were examined using anonymous self-administered questionnaires. For these predictors, we produced original items with reference to the concept of ethical development and the teachings of Mencius. The subjects were medical students at the Kitasato University School of Medicine, a private university in Japan. A total of 518 students were analyzed (response rate, 78.4%). The average age of enrolled subjects was 22.5 ± 2.7 years (average age ± standard deviation). The average age of 308 male subjects was 22.7 ± 2.8 years, while that of 210 female subjects was 22.1 ± 2.5 years. The item, “Excessive measures to pass the national examination for medical practitioners,” was significantly associated with “a sense of resistance to patients' rights.” However, other items, including basic attributes such as age and gender, were not significant predictors. If students spent their school time only focusing on the national examination, they would lose the opportunity to receive the ethical education that would allow them to respect patients' rights. That ethical development cannot easily be evaluated with written exams. Thus, along with the acquisition of medical knowledge, educational programs to promote medical students' ethics should be developed.