An ozone generating apparatus in which the temperature distribution in a dielectric tube can be more uniform so as to increase the discharge power density, the size of apparatus can be miniaturized or the capacity can be increased. An ozone generating apparatus comprising a sealed vessel, two tube sheets made of conductive metal plate having a hole formed therein which are provided at a predetermined interval to divide the inside of the sealed vessel into three spaces; a metal tube formed so as to connect holes of the two tube sheets, a dielectric tube which is inserted into the inner part of a dielectric tube so as to have a predetermined gap between an outer wall and an inner wall of a metal tube and a metal electrode formed inside the dielectric tube, wherein an alternating current voltage is applied between the metal tube and the metal electrode, a material gas including oxygen flowing in a gap is discharged so as to generate ozone, and a discharge suppressing member is provided at a part of gap facing a tube sheet.