This paper analyzes a virtual work of the knee and hip joints of bipedal walking robots. For the purpose, we consider a model of bipedal leg mechanism with a compliant foot and a typical walking pattern. We also check the torque characteristics at the joint space propagated from the space of the foot contacting a flat and stiff surface, and present the works accumulated at the joint space. As a result, it is shown that this analysis is useful for evaluating the fatigue of the leg mechanism by the physical walking contact between the foot and the surface, and it is applicable for improving the compliant characteristics at the foot space by employing a proper footgear.