Introduction: Children with autism spectrum disorder (ASD) face numerous challenges in transitioning to elementary school, which can cause confusion for the children and concern among their parents. Introduction: This study aimed to identify the process of school transition from kindergarten to elementary school for children with autism spectrum disorder in Japan, by evaluating the effectiveness of a school transition program. Methods: A focus group interview was conducted with seven parents who participated in a transition program. They were asked about communication with the teachers, support obtained from the school, and their experiences after their children entered elementary school. After the group interview was recorded and transcribed, the data were analyzed using inductive content analysis to determine the parents' experiences of the school transition process. Findings: Six main themes emerged from the focus group interview: (1) acquisition of prerequisite skills; (2) adjustment in dealing with children with ASD; (3) communication between school and home; (4) communication between peers and children with autism spectrum disorder; (5) collaboration with special needs education teachers; and (6) the principal's understanding of special needs education. Conclusion: These findings provide an overview of the challenges and possible solutions to support school transitions for children with autism spectrum disorder in inclusive educational environments.