An auto focus module of an image capture device is provided. The auto focus module comprises at least one gear, a nut, a lead screw and a driver. The gear has at least one first extension and a first through hole. The nut has at least one second extension and a second through hole. The lead screw penetrates the first through hole and the second through hole. The driver drives the lead screw and the gear so that the lead screw and the gear move relatively along the axis of the lead screw. The nut and the gear terminate approaching toward each other after the first extension and the second extension lean against each other.