This research aimed to study the perception of changes in the school field after the implementation of the 2015 revised curriculum which emphasizes competency-based education. 215 secondary school teachers participated in the survey of this study. The teaching subjects of the teachers consisted of 9.3% in science, 10.75% in social studies, 11.2% in music/art/physical education, 14.0% in Korean language, 16.7% in mathematics, and 26.5% in English. It was found that teachers emphasized cultivating students’ competencies in their classes, and that they were trying to realize the six key competencies in their classes. It was also found that teachers have a perception that teaching methods attracting students’ participation, such as small-scale discussions and group projects, are efficient ways to cultivate students’ competencies. There were many opinions which the current evaluation system did not assess students’ competencies adequately. The lack of practical teachers’ guides and parents’ awareness, however, were analyzed to be obstacles to competency education. We concluded that students’ interests in themselves and teachers’ dedication were important as factors influencing students’ competency development.