Abstract: A position adjustment device includes a housing, a limit rod, a movable rod, a rotation knob, a linking member, a driven member, a worm wheel, a direct-current motor, and a circuit board. Thus, the movable rod is movable to adjust the position and projecting angle of the headlight so that the direction of the headlight can be adjusted according to the slope of the road so as to provide a larger illuminating zone and a better viewing angle, thereby protecting the driver's safety when driving the car. In addition, the position and angle of the headlight is adjusted manually or in a motorized manner, thereby facilitating the user adjusting the direction of the headlight.