question: Background: A novel coronavirus, SARS-CoV-2, has spread widely throughout the world. To reduce the spread of infection, children are prevented from going to school and have fewer opportunities for in-person communication. Although the pandemic has affected the everyday lives of children, its impact on their development is unknown. This cross-sectional study compared Japanese children’s socio-emotional behaviors and skills for operating digital devices before and during the pandemic. Methods: : Parents completed a web-based questionnaire before and during the pandemic for children aged 0-9. Children’s socio-emotional development in the context of everyday life was assessed using the Strengths and Difficulties Questionnaire (SDQ). Children’s basic touch interaction skills to operate digital devices and skills to use functions of digital devices were also measured. Results: : The results indicated that during the pandemic, children were more prosocial, experienced more problems in their peer relationships, and had better digital skills, but no differences were found in emotional symptoms;conduct problems;and hyperactivity between, before, and during the pandemic. The differences in digital skills were explained by the duration of children’s media use. Conclusions: : Overall, our results suggest that the pandemic may have an immediate impact on children’s socio-emotional behaviors and digital skills. Trial registration: Registration type: OSF Preregistration.Date registered: April 27, 2020.Registration from osf.io/tfh4k.(https://osf.io/c7p6b)