The purposes of this study were to examine the characteristics of infant-teacher interactions and to investigate the components of synchrony in interactions between infant and teacher. Synchrony means a qualitative interactional style between two people. To be specific, it is a relatively new concept that includes qualitative features of the interactions characterized by reciprocity, shared emotions and affections, and balanced interactional attempts and responses between the two. The subjects of this study were 40 infants (13-20 month olds) and 20 teachers who were in charge of 0-year-old classrooms in workplace childcare centers located in Seoul or Gyeonggi-do. In terms of research methods, observations were conducted for 10 minutes per dyad during free play time without interruption. The results of this study are as follows. First, in general, individual and dyadic characteristics were found in the interactions between infant and teacher. Second, according to the variables, significant differences in interactional synchrony were found in the teacher’s whole teaching experience and infant teaching experience. In addition, there were positive correlations between the duration of the two being together and their interactional synchrony. Third, it was proved that shared emotions (both positive and negative), balanced compliance to the other’s interactional attempts, and reciprocity were the key components to explain interactional synchrony. There were highly positive correlations between interactional synchrony and the infant’s interactional attempts and between interactional synchrony and the infant’s compliance to the teacher’s interactional attempts; on the other hand, there existed a negative correlation between interactional synchrony and the teacher’s compliance to the infant’s interactional attempts.