PURPOSE: To recognize that body of a worker is securely grounded and not charged with static electricity by providing a means for indicating whether or not a grounding electrode is perfectly grounded to a worker.

CONSTITUTION: A worker connects a grounding wire 5 to an electrode 4, and closes a power source switch 17. In the case where a worker is normally grounded, current flows through a resistor 18 to generate the voltage in the resistor 18. This voltage is amplified by a reverse amplifying unit 19, and furthermore, reversed by a reverse amplifying unit 20, and applied to a base of a transistor 21. Consequently, the transistor 21 is electrified, and a light emitting diode 9 is lighted, and a worker can recognize that the worker is normally grounded and not charged. In the case where a worker is not normally grounded, current is not flowed to the resistor 18, and the transistor 21 is electrified, and the diode 9 is not lighted. Consequently, the worker can recognize that the worker is not normally grounded.