An ozone generating apparatus is provided which includes a pair of electrodes for producing a discharge by the application of an ac voltage therebetween, and at least one dielectric provided between the pair of electrodes. A source gas containing oxygen is provided into a discharge space in which the discharge is produced to generate ozone by the action of the discharge. A surface lying between at least one of the pair of electrodes and the discharge space and in contact with the discharge has a surface resistivity of 104Ω to 1011Ω. The source gas provided into the discharge space includes ultrapure oxygen having a purity of not less than 99.9%.