This study investigated the relationship between the development of the socio-emotional abilities of Japanese children between the ages of one and 2 years, and the quality of care they receive at their childcare centers. The participants were 872 pairs of parents (M = 34.13 years old) and their children (M = 25.65 months old) who attended one of 57 public childcare centers in urban Japan, as well as 373 childcare teachers (M = 37.26 years old) who conducted classes. Parents rated their children’s social competence and problem behaviors, and the child-centered teaching attitudes in classrooms were rated by the teachers. The results revealed that the child-centered teaching attitudes in classrooms contributed significantly to low problem behavior among 1- to 2-year-old children, even when child variables (age, sex) and family variables (family income, parent’s education, and parent’s responsibility) were controlled. Child-centered teaching attitude had a particularly pronounced effect when the family variable of parent responsibility was low. This is the first empirical evidence of this relationship in a non-Western country. Our results suggest the importance of child-centered teaching attitudes for children who experience long hours of childcare outside the home, along with teachers’ beliefs and attitudes regarding the quality of early childhood education and care, and related professional training.