To obtain a maintenance-free ion generator in which electrodes are not heated to a high temperature; dry air is not required for the air as the raw material for ozone; nitric acid is not generated by the moisture and NOx in the air; the corrosion of the electrodes and consequent failure in ozone generation do not occur; and the cleaning and exchanging of the electrode sections are not required at the time of continued use.

The ozone generator shuts off the electrodes from the air, wherein double cylindrical dielectric substances are composed of the dielectric substance A of an inner side and the dielectric substance B of an outer side; the electrode A of stainless steel foil etc., is stuck to the inner side of the dielectric substance A and the electrode B of stainless steel foil etc., is stuck to the outer side of the dielectric substance B to cover the outer periphery of the electrode B so as to prevent contact of the air therewith; a holder 1 and a holder 2 shut off the air on the side face of the dielectric substance A; a discharge space is provided between the outer side of the dielectric substance A and the inner side of the dielectric substance B; an air introducing port provided at the holder 1 and an ozone emission port provided at the holder 2 are communicated with the discharge space; and a high voltage power source is applied to the electrodes.