Wheelchair badminton was a new event at the Tokyo 2021 Summer Paralympic Games. To develop a motor-learning support system, this study aimed to quantify the motion of a world-class wheelchair badminton player. For this purpose, static and dynamic posture analyses were conducted. An ex-member of the Japanese national wheelchair badminton team volunteered for this study. Three-dimensional scanning was used for static posture analysis, and the deformation of the lower side of a wheelchair seat during shuttle hitting was quantified. The wheelchair customized for the participant demonstrated less change in the maximum deformation and its position in different postures. Next, inertial sensors were used for the dynamic posture analysis. The relative angle between the upper and lower trunk was recorded. The participant moved back and forth five times over a distance of 3 m. During the forward-to-backward transition, the first trunk flexion acts as a brake for forward movement, while the second trunk flexion acts as an accelerator for backward movement. During the backward-to-forward transition, the first trunk extension acts as a brake for backward movement, while the second trunk extension acts as an accelerator for forward movement. Based on these results, we will develop a feedback system utilizing visual, auditory, and tactile modalities to guide new wheelchair badminton players toward these propulsion patterns. We aim to promote sports for disabled individuals.