The specialty of Korean teacher does not means teacher's personal excellent talent or ability. It means ‘Subject Expertise’. In this study I took the concrete shape of the subject expertise of Korean teacher as ‘comprehension and evaluation of real language’, ‘comprehension and evaluation of the student's language culture’, and ‘ability of analysis, evaluation, and production of textbook’. For the sake of improving these subject expertise, I proposed some of institutional supports as follows; first, we need to prepare the basic textbooks for the curriculum of Korean teacher training or retraining. Second, It is desirable for the college of education to organize and practice the courses of the major teaching profession. Third, the term of teaching practice system must be sufficiently extended for training to develop the teaching skills and to broaden preservice teachers' outlook on the class. Fourth, teacher retraining system should be reorganized for suitability to develop teachers' linguistic competence, communicative proficiency, and teaching ability. And Fifth, the teacher training course of the general colleges and graduate school in education must be reinforced in according with the curriculum of college of education.