The purpose of this study is to evaluate the educational value of teaching practicum in secondary schools. For this purpose, on the basis of literature review and interviews, three evaluation criteria for measuring educational value of teaching practicum are constructed as follows: (1) practical teaching competence, (2) readiness for teacher, and (3) maturity in character. A total of 29 pre-service teachers in the College of Education at Seoul National University in South Korea participated voluntarily in this study, and their practical teaching competence, readiness for teacher, and maturity in character were measured twice before and after teaching practicum. As a result, the teaching practicum had significantly improved pre-service teachers' practical teaching competence, readiness for teacher, and maturity in character. In other words, teaching practicum increases the educational value. This study provides a conceptual framework and three instruments for measuring the educational value of many other teaching practicums.