A system allowing automatic detection of the end of winding of a cable on a winch comprises an optical detector which emits, in the direction of the cable, a light beam which illuminates a given zone through which the cable travels in the course of its winding. The detector is associated with a specific marking, strongly reflecting, positioned on a section of the cable close to its end, such that, when this section enters into the zone illuminated by the detector, it reflects the beam in the direction of the detector which detects this reflected beam and which then signals that the cable is almost at the end of winding. The detector, placed in a fixed position at a given distance from the cable, is also associated with a light waveguide interposed between the cable and the optical detector.