The purpose of the present study was to clarify the process and factors of the improvement of kindergarten teachers’ expertise in early childhood education through conferences. Thirteen kindergarten teachers participated. Their discussions about early childhood education at conferences were recorded. As a result, we demonstrated their process of redefining the kindergarten teachers’ framework and improving the teachers’ expertise by exchanging ideas with their colleagues. This study also identified two factors for improving the kindergarten teachers’ expertise in early childhood education through conferences: (1) disclosing and asking about your own issues and worries, and (2) asking questions and making suggestions based on your own experience.