Background and aims: The number of children in special education schools has increased in Japan. This study aimed to examine the association between special education school enrollment and the health and social relationships of mothers with children in these schools using population-based samples in Japan.Methods and procedures: This study used data from the Kochi Child Health Impact of Living Dif-ficulty (K-CHILD) study in 2016. First, fifth, eighth, and eleventh-grade children in all schools in Kochi prefecture were included (n = 12,623). Associations between school type (regular or special education school) and maternal physical and mental health and social relationships were investigated by multivariate regression models.Outcomes and results: There were 134 children in special education schools (1.1 %) and 12,489 children in regular schools. Mothers of children in special education schools were more likely to have higher body mass index (BMI), poorer mental health and lower neighborhood relations score. Mothers of children in regular schools had higher BMI when their children had higher behavioral problems. Conclusion and implications: Mothers of children in special education schools are at risk of obesity, poor mental health, and having fewer social networks. Services and support should be expanded for caregivers based on their child's behavioral problems and school system.