Testing of "open circuit", "short circuit", and "wrong wiring", which is generally called Wiring Testing, is fundamental and important. As a method, check the continuity between the terminals of the connector with a buzzer or lamp manually by sound or light. However, this method is time-consuming and it is difficult to check all wiring accurately. A wire harness testers were created to improve quality and complete the testing in a very short time. With our testers "nacman", the test target having 128-point can be completed in less than one second without human error.