An ozone generating device includes three or more cooling channels each having a through-hole formed in a central region thereof and a coolant flow path formed therein. The cooling channels are arranged side by side such that the through-holes thereof overlap with one another. The ozone generating device further includes electric discharge units interposed between the cooling channels adjoining each other and configured to generate electric discharge when applied with a high voltage. Each of the electric discharge units has a central hole formed in alignment with the through-hole. The ozone generating device is configured such that, when the electric discharge units are applied with a high voltage with the cooling channels kept grounded, oxygen supplied to the electric discharge units is decomposed into ozone which in turn is discharged through an internal space defined by the through-hole and the central hole.