Objective: Using data from the Panel Study on Korean Children, this study investigated the influence of teacher’thoughts about the transition from ECEC to primary school in relation to learner-centered teaching methods and children’s school adjustment. Methods: We analyzed the longitudinal data of 658 seven-year-olds from the 8th and 9th waves of the panel study of Korean children collected by the Korea Institute of Child Care and Education in 2015 and 2016. The main analysis method was Structural Equation Modeling(SEM). Results: First, theachers’ thoughts about the transition from ECEC to primary school was noteworthy. Second, the more concern a theacher’ had about transition, the higher their learner-centered teaching method. Third, teacher’ concern about transition influenced children’s school adjustment. Fourth, a teacher’s learner-centered teaching method mediated concern about children’s transition and school adjustment in the first year and the second year. Conclusion/Implications: According to the results of this study, 1st grade teachers’ concern about the transition from ECEC to primary school has been found to be predictors of children’s school adjustment.