<p>An ozone generating apparatus comprising at least one ozone generating unit including: two electrodes (2,31) mutually opposed to generate discharge in response to high voltage applied therebetween; at least one dielectric (4) interposed between the electrodes; and a gas supply mechanism to supply an oxygen-containing gas between the electrodes so as to generate ozone by the discharge; wherein a discharge space (5) has a gas pressure of one atmosphere or more. The invention is characterised by a choice of discharge gap length (less than 0.4 or less than 0.6 mm) and by the product of the gas pressure and the discharge gap length.</p>
