The purpose of this study is to develop and practice a instructional coaching program suited to schools. This study investigates the perception of instructional coaching, change in the culture in a school, and promoting factors and limiting factors in order to consider implications of the school-based instructional coaching program. The topics of this research are as follows. First, what is the school-based instructional coaching program, based on teachers reflection? Second, what changes did teachers recognize when exercising the school-based instructional coaching program? Third, what are the promoting factors and limiting factors of the changes at schools where the instructional coaching programs were implemented? Fourth, what does this study imply about operating this instructional coaching program? To investigate this study topic, a instructional coaching program was applied to S middle school. The data from the survey and focusing group interview were analyzed and interpreted systematically, and some results were produced. As a result of the study, the following are changes that teachers recognized in the school where the instructional coaching program was applied. First, professional and collegial relationships among teachers were facilitated. Second, teachers began to share what they are concerned about. Third, many teachers restored the identity as a teacher. Fourth, many teachers began to reflect on their teaching. Fifth, mutual relationships between a teacher and students were developed. Sixth, collaborative learning increased after practicing the new teaching. The following is the result of the study on promoting factors and limiting factors to understand the context of the change in the culture at a school. The promoting factors are trusting the leading group for the change, having intimacy among teachers, building an adequate support system at a school. The limiting factors are the fear of an open class, failure in establishing trusting relationship among teachers, and the hectic schedule at a school. This case study about the application of the instructional coaching program at the S middle school implies three things. First, this case study demonstrates that the instructional coaching can be performed in a school. Second, the application of the instructional coaching program at the S middle school gives insight into development of teacher competency, and teacher collaborative learning. Third, the S middle school case implies changing the paradigm is needed, from teacher learning community to teacher caring community providing emotional support for one another. This study is significant in the sense that a school-based instructional coaching program was designed, it was implemented for a relatively long time, and changes in the school that teachers recognize were studied. Further precise study of the instructional coaching program is required.