We focus tactile stimulus on a sole during walking to clarify mechanisms of fall and walking adapted for irregular terrain. Therefore, this paper proposes the development of the novel optical forces sensor which can measure 3-axis distributed forces acting on a sole during walking. This sensor can measure how much force in which direction a sole loads the floor in detail when human walks. The construct of the 3-axis distributed forces sensor using silicone rubber is reported. To measure the 3-axis distributed forces, the sheet of silicone rubber which has many circular truncated cone projections is developed. To detect 3-axis forces from the deformation of a projection by High-speed cameras, we conducted experiments to verify the relation between the force and the deformation of a projection. From results of experiments, 3-axis forces can be detected from the deformation of a projection.