The purpose of this study is to investigate the process of kindergarten teachers establishing their collective expertise in a teacher learning community. Data collection was conducted centering on the meeting of a total of 10 sessions of teacher learning communities with 4 teachers from G public kindergartens as study participants, and dialogue data for each session were analyzed using a verbal interaction analysis framework. As a result of the study, it was confirmed that the process of forming group expertise with three characteristics overlapped over time, and factors affecting the process of forming group expertise were derived. Based on these results, it is significant in that the meaning of the teacher learning community and the direction of teacher education in the educational field were presented in various ways. In addition, in order to continue and dynamically lead the teacher learning community, it was suggested that background knowledge and reflective thinking based on the teacher's experience, constant practice, smooth interaction skills, and mutual respect were important.