A target cable has first and second ends that are identified in advance. All conductors of the target cable are electrically short-circuited at the first end of the cable. At the second end of the target cable, pilot signals are infused into a optional number of the conductors of the target cable. The pilot signals produce leakage flux from the target cable anywhere along the target cable. At a given site where the target cable is going to be identified, a magnetic sensor is successively applied to many cables laid around the target cable, to detect the leakage flux. By finding a cable that provides the leakage flux caused by the pilot signals, it is determined that the cable is the target cable.