AimThis study examines the impact of COVID‐19 pandemic‐induced behavioral restrictions on child psychiatric inpatients in Japan, particularly focusing on limitations placed on outings and overnight stays as infection‐control measures.MethodsData were collected from inpatients from the children's mental health registry between January 2016 and December 2022. The clinical data, such as age, gender, diagnosis, result of polymerase chain reaction (PCR) tests, frequency of outings and overnight stays before and after the pandemic, were compared.ResultsDuring the COVID‐19 pandemic, the decrease in both outings and overnight stays among child psychiatric inpatients in Japan was statistically significant. As a result, home interactions with families decreased. In addition, diagnoses of hospitalized children increased significantly in cases of eating disorders and decreased in diagnoses of autism spectrum disorders.ConclusionThese results underscore the need for flexible, individualized approaches to infection control that consider the mental health of hospitalized children.