PURPOSE: To perform potential treatment generating no danger of an electric shock at all, by always holding the potential of a human body to earth potential during treatment.

CONSTITUTION: A potential generator 10 has an earth terminal 10a and an output terminal 10b and potential for potential treatment is outputted from the output terminal 10b. The outer periphery of the conductor 16 of a treatment electrode 14 is coated with an insulator 17 and an earth electrode 12 is directly brought into contact with the surface of the skin of a human body P being an object to be treated and a condenser is formed between the human body P held to earth potential and the treatment electrode 14 outputted from the output terminal 10b of the potential generator 10 and having the insulator covering the outer periphery thereof by the contact of the earth electrode 12 wit the human body P and charge is applied to the human body from earth by the electric field formed between both terminals of the condenser. Since the treatment voltage from the potential generator is not directly applied to the insulated human body and, therefore, the potential of the human body during treatment is always held to earth potential regardless of the magnitude and polarity of the output potential of the output terminal 10b, potential treatment can be performed in any case without generating the danger of an electric shock.