Background & Aims: Various insoles have been developed, but little objective evaluation of their effectiveness has been conducted. We investigated the effect of insoles supporting the cuboid bone and anterior part of the calcaneus in healthy individuals.Methods: The subjects included 18 healthy males and females. They walked in standardized shoes with a flat insole (hereinafter, FI, a flat insole made of polyurethane without an arched shape on the surface) and a carbon fiber insole (hereinafter, CFI, made of carbon and supporting the cuboid and anterior part of the calcaneus). We used a three-dimensional motion analysis device and a force plate to analyze gait and quantitatively compared the effect of CFI.Results: The CFI reduced ankle power without reducing walking ability. In particular, with regard to the left-right difference in ankle joint sagittal plane power, we found that when the left-right difference was large, the use of CFI reduced the left-right difference in power.Conclusion: The burden on the muscles of the lower limbs on one side is reduced, and sports performance, including walking, can be maintained.