To provide a transmission wheel system, capable of stepping comfortably and peacefully by energy storage of reciprocating displacement.

A one-way transmission device is provided in a prime mover pulley driven by a power source having a one-way output characteristic, between the prime mover pulley and a body or between a prime mover wheel shaft joined to the prime mover pulley and the body, and when the prime mover pulley drives a driven pulley so that the speed ratio between the prime mover pulley and the driven pulley periodically changes, an auxiliary pulley (312) of an auxiliary pulley assembly is simultaneously moved, and stores prestress energy, and when force added to the driven pulley via a transmission belt by the prime mover pulley is 0 or relatively weak, the auxiliary pulley (312) emits energy, and the force is added to the transmission belt, and the transmission belt is coupled with the prime mover pulley, and the transmission belt is moved, and the driven pulley rotates in the original rotation direction, and also feeds back kinetic energy.