This study aimed to reveal how the recent COVID-19 pandemic affected the mental health of children with disabilities receiving child developmental support and after-school day services. A survey questionnaire was sent to 1,003 facility managers, and 276 (27.5%) responded. After excluding invalid responses, 239 valid responses were received (valid response rate: 86.6%). A total of 62 (25.9%) offices responded that the spread of the COVID-19 pandemic caused instability or worsening of children’s mental health. The data were analyzed to compare the differences between facilities where children’s mental health was unstable and those where it was not. The findings of this study highlighted the relationship between the mental well-being of children with disabilities receiving support and services at the facilities during the COVID-19 pandemic. The mental stress caused by anxiety and environmental changes related to the pandemic may have adversely affected the children who used those services. The study’s results offer guidance on how child developmental support and after-school day services can implement infection control in the future.
