The configuration is made simpler, and deterioration is prevented. At first, a pilot potential with no risk of electrical shock is applied to an energization base (5), the induced current in a seat electrode (7) is measured, whether or not a high voltage can be applied is determined by changes in a current value associated with the seating of a patient (A) to be treated on a chair (4), and when determined that the high voltage can be applied, a therapeutic high voltage is applied to the energization base (5). In addition, whether or not output block is necessary is determined by changes in a current value associated with the separation of the patient (A) to be treated from the chair (4), and when determined that the output block is necessary, the output is blocked.