[Purpose] The purpose of this study was to report that a physical therapist qualified for swimming instruction can provide swimming instruction to children with spastic paraplegia due to cerebral palsy. We examined the role of the physical therapist in the support. [Participants and Methods] Two elementary school children with cerebral palsy participated in this study. The swimming program consisting of 6 sessions was performed over 6 months in an indoor swimming pool. Each session lasted for 30 minutes and was instructed by a trained physical therapist. The 5 categories for evaluation were motor function, muscle tone, activities of daily living, swimming skill, and satisfaction level. [Results] Case A showed improvement in streamline floating distance and 15-m time. Case B could not swim 15 m in the first session but completed 15 m within 102 s in the last session. The 3 other categories besides swimming skills did not improve. [Conclusion] With a skilled physical therapist’s instruction, children with cerebral palsy may improve their swimming skills over a limited number of sessions without any adverse events.