The present invention relates to a padlock having a metal U-shaped rod seated in an outer polymer body. The padlock has a one-piece actuating device that is formed by a base that is operatively associated with the core of the cylinder unit, an elongate body portion that is positioned above the base and has end portions designed to be seated in corresponding recesses of the rod, and a stop portion that projects laterally from the elongate body portion. Rotating the core of the cylinder unit to open the padlock causes the rotation of the base of the actuating device, and consequently the rotation of the elongate body, causing the end portions of the elongate body to come out of the recesses in the rod.