To change the lower limb muscle activities while walking, we propose a muscle activity controlling system that dynamically changes shoe insoles. We conducted a preliminary experiment on a prototype system to determine the system's validity. In this experiment, we analyzed how tibialis anterior and gastrocnemius muscle might change their activities depending on each insole condition. The results lead us to conclude that our system may affect changes in the duration percentage of tibialis anterior muscle activation when we change the heel part shape, and that it may change the maximum amplitude of gastrocnemius muscle activation when we change the arch part shape and hardness.