Background In Japan, students' poor adjustment to school life such as school refusals has been recognized as a nation‐wide problem. In this study, we examined the link between the absence of mothers' active engagement with their infants at 6 months and children's risks of poor adjustment toward elementary school life at the ages of 5.5 and 11. Methods We used a Japanese national longitudinal survey (n = 43 132) with 11 years of follow‐up. Because of social patterning in how mothers engage with their infants, we employed propensity score matching analyses to control for confounding by socio‐economic and other factors. We matched mothers with active engagement and those without on various social and parental characteristics such as educational attainment and household income. Results and Conclusions Among matched pairs, we observed higher risks of poor adjustment to school life at both 5.5 and 11 years among Japanese children who lacked mothers' active engagement at 6 months. For example, the relative risk was 1.46 [95% confidence interval: 1.10, 1.94] for inability to get along with others in a group setting at the age of 5.5 years and 1.29 [1.10, 1.51] for inability to get along with teachers at the age of 11 years. Our findings corroborate previous findings, which emphasize the importance of providing an enriched environment for infants' social development and may indicate the need for an intervention for caregivers who lack appropriate nurturing skills.