The purpose of this study is to examine the mediating effects of teachers' psychological well-being between teachers' attachment history and child-teacher relationships. The participants of this survey were 342 teachers from 41 day care centers and 11 kindergartens in four metropolitan cities and five provinces in Korea. The collected data were analysed through frequency and percentage calculation, Pearson's correlations, and the mediation methods suggested by Baron & Kenny(1986) were calculated by using SPSS 21.0. The findings are as follows. First, the percentage points of the attachment history of early childhood, the teachers' psychological well-being and the child-teacher relationship were higher than the average. Also, all the variables had correlations. Second, the teachers' psychological well-being partly mediated the relations between attachment history and child-teacher relationships. These results imply that teachers' psychological well-being is needed for positive child-teacher relationships, and can provide policy implications for teachers' psychological well-being in order to improve the quality of child-teacher relationships.