A pulse echo wave tester can locate a fault in paired cables. However, when a paired cable comprises branched cables and different types of wire gage along a length, the pulse echo tester cannot detect faults because of complicated pulse echo waves. This paper describes a new pulse echo tester which can locate a fault by the correspondence between measured and calculated pulse echo waves in case of such complicated cable structures. First, we derive a calculation method of pulse echo waves in complicated cable structures. The fault is located by the condition that the difference between measured and calculated pulse echo waves becomes the minimum value. Next, location errors and the distance limitation of a fault location are described considering variations of cable parameters. It is clarified that the distance limitation of a fault location depends mainly on a pulse period. In the experiment, the fault is located in a 2-km paired cable with a branched cable. As a result of this test, a fault location error is about 10 m.