The range of motion of the human lower limbs is comparable to that of the upper limbs, which suggests the feasibility of controlling a device with multiple degrees of freedom using the lower limbs. If this can be achieved, it could lead to an extension of human capabilities. In order to ensure accurate control using the user’s feet, it is important to understand the characteristics of foot motions, especially those of the exerted force. This study experimentally investigates the force characteristics of the foot using an isometric device that can measure the exerted force. The experimental results show when intending to exert forward-directed force, downward force is also generated. Additionally, we revealed that when intending to exert downward or sideways forces, forces in other directions also become prominent. Considering the fundamental motion characteristics of the lower limbs, we proposed an operation system and conducted experiments in a virtual space. A method based on conversion equations is proposed to compensate for the unintended force. An experimental comparison of the proposed method and the conventional method shows that the proposed method leads to significant improvements in the clear time, operation path length, and deviation from the ideal path, verifying its effectiveness. Especially during the main stages of the operation, the proposed method allowed for more accurate control, with a maximum enhancement of 16% in accuracy.