Abstract: A torque limitation device in a retarding mechanism includes a worm shaft engaged with a worm gear in a gear case and operated by a motor. The worm gear is pressed by an elastic adjustment assembly and indirectly rotates a transmission shaft which actuates the entire machine to work. When the transmission shaft is obstructed or in a rough rotation to cause an torque increasing, the worm shaft and the worm gear are immediately begin an idle running and the worm gear become slippery with the transmission shaft so as to prevent the motor from damaged for overloading.