The present invention discloses a resistance force control structure of driven pulley device, which is pivot mounted on a wheel of a driven pulley device, and primarily uses damping oil or a magnetic force to achieve a resistance effect. The magnetic force portion can also be added to a gear structure to present another configuration of a resistance force control structure to achieve change in magnetic force to increase the stabilizing effect of a wheeled frame. Moreover, an adjustable mechanism enables the user to control changes in the height of the damping oil level or magnetic force strength to control the rotational speed of a wheel.
