The educational approach of empathy has been prominently mentioned as a possible solution to the dehumanization occurring as a byproduct of the rapid development of science and technology in modern society. This study aims to identify the characteristics of Korean adolescents on the empathy factor, as a core competency of twenty-first century education, and the applicability of the empathy scale. This study analyzed 688 Korean adolescents' cognitive and affective empathy using the Interpersonal Reactivity Index (IRI). Korean adolescents showed an increase in all four factors of IRI as they got older. According to gender, females' empathy was higher in all four factors. In terms of the validity of the scale, the difference in subscales by gender was obvious. But, the instability in subscales by age of the Perfective Taking (PT) and Personal Distress (PD) was shown. Especially, PD had an insignificant correlation with other subscales. By revealing the limitations of the IRI, this study suggested ways to improve it. Therefore, this study will contribute to the educational foundation of Korean adolescents' empathic ability.