The present invention removes electric charges that have accumulated on an electrode, and resets the voltage required for discharge. A discharge device 9 is provided with a discharge electrode 12, a counter electrode 17, a high-voltage electrode 19, a ground electrode 20, a control unit 30, a high-voltage power supply 40, etc. The counter electrode 17 is formed of a conductive resin having a volume resistivity of not more than 107 Ω·cm. When the output voltage of the high-voltage power supply 40 is less than a trigger voltage A, the control unit 30 executes a discharge mode, and causes the high-voltage power supply 40 to generate a discharge between the discharge electrode 12 and the counter electrode 17. When the output voltage of the high-voltage power supply 40 has reached the trigger voltage A, the voltage output from the high-voltage power supply 40 is suspended temporarily, and a transition is made to a voltage reduction mode. Further, when the length of time that has elapsed since the transition to the voltage reduction mode reaches a prescribed voltage reduction time, a transition is made back to a discharge mode.
