PURPOSE: To discriminate whether the circuit is in the shorted state or not definitely by comparing the voltage drop in a circuit under inspection, which supplies the inspecting current at a specified value through probes, with a refer ence voltage, and reporting the conducting state of the circuit with a reporting device based on the result.

CONSTITUTION: Probes 2A and 2B are brought into contact with both ends of a circuit under inspection 1. When the circuit 1 is in the complete shorted state, the voltage of a battery 4A is applied on a resistor 21, and the voltage at the probe 2A becomes lower by the amount of the voltage drop than a reference voltage, which is set with a resistor 42. The voltage is inputted to a comparator 31. The output thereof turns on a transistor 51 through a resistor 52 and operates a buzzer 3. When the circuit 1 has a wraparound circuit or the like, the voltage caused by the voltage drop of the circuit is taken out with the probe 2A and inputted to the comparator 31. When the input voltage is higher than the reference voltage, the transistor 51 becomes OFF, and the buzzer is not operated. Thus, whether the circuit 1 is completely shorted and has the wraparound circuit or the like or not can be definitely discriminated and reported.