[Purpose] The aim of this study was to determine the immediate effect of short-foot exercise (SFE) on the dynamic balance of subjects with excessively pronated feet. [Subjects] This study included 18 subjects with excessively pronated feet (navicular drop ≥ 10 mm) selected using the navicular drop test. [Methods] The limit of stability (LOS) was measured to determine the changes in the dynamic balance from before and after SFE in the standing and sitting positions. [Result] After the SFE, LOS increased significantly in all areas, namely, the left, right, front, back, and overall. [Conclusion] SFE immediately improved the dynamic balance of subjects with excessively pronated feet. Subsequent studies will be conducted to examine the effects of SFE performed over the long term on postural stability.