The purposes of this study were to quantify the function and sequence mechanism of support leg joint torques and to investigate influences of shoe sole bending stiffness on the mechanism in the acceleration phase during sprinting motion. The functional roles of support leg joints at 1st, 3rd, 5th and 7th steps from the crouch start were analyzed by quantifying dynamic contribution of the joint torques to the generation of whole-body CG acceleration using the equation of whole-body motion. Since ankle joint plantar torque, which shows eccentric torque generating type in the first half of stance phases at individual steps, is the largest contributor to the body propulsion and support, the mechanism of generating dorsal angular velocity at ankle joint was investigated by using the equation of whole-body motion to clarify the contributors that induce the eccentric ankle joint torque. Then, the effect of shoe sole bending stiffness on the dynamic contributions of joint torques was investigated. The characteristics of sole bending stiffness about MP joint axis for sprinting spikes and training shoes are approximated by the polynomial function. The results obtained in this study indicate that 1) body propulsion and support are mainly caused by the ankle joint torque in the acceleration phase during sprinting motion, 2) the major contributor to eccentric ankle joint torque, which is observed in the first half of stance phase, is hip joint torque, and 3) the dynamic contribution of support leg joint torques are affected by the step number and the sole bending stiffness.