To provide a generator capable of generating plasma and ozone with high efficiency and easy to handle, with a simple structure. An electrode part 10 is formed of electrodes 11 and 12 without dielectric material interposed therebetween. An arc-extinguishing capacitor 13 as a charge storage part for storing charge is connected in series to the electrode part 10. An AC power source 15 generating plasma by causing self-arc-extinguishing discharge between the electrodes 11 and 12 by applying AC voltage to charge and discharge the arc-extinguishing capacitor 13, is connected to both ends of a circuit in which the electrode part 10 and the arc-extinguishing capacitor 13 are connected in series. The arc-extinguishing capacitor 13 and one electrode 12 of the electrode part 10 connected thereto are unitized, for making the electrode part multi-polarized. A unit is constituted of a floating electrode serving as both of the one electrode 12 of the electrode part 10 and one electrode of the arc-extinguishing capacitor 13, an insulating material provided around the floating electrode and a grounding electrode provided around the insulating material.