An ozone generating apparatus, comprising: - a hermetically sealed vessel; - two tube sheets (90, 91) each comprising a conductive metal plate having a hole formed therein, which are provided in the hermetically sealed vessel so as to partition its inside into three spaces; - a metal tube provided so as to connect the holes of the two tube sheets (90,91); - a dielectric tube with a metal electrode formed inside thereof, which is held inside the metal tube so that a predetermined gap is given between an outer wall of the dielectric tube and the inner wall of the metal tube; and - an AC power supply for applying an AC voltage between the metal tube and the metal electrode; - the ozone generating apparatus being configured to flow an oxygen-containing source gas from either one of spaces placed at both end sides among the three spaces to the other one of the spaces placed at both end sides, through at least the gap; - to generate ozone by discharging the source gas flowing through the gap while placing the metal tube and the tube sheets (90, 91) at ground potential and placing the metal electrode inside the dielectric tube at high potential; and - to cause cooling by flowing cooling water in a space partitioned by the two tube sheets (90, 91), an outer wall of the metal tube, and an inner wall of the hermetically sealed vessel; and - the ozone generating apparatus further comprising a discharge suppressing member formed of a metal plate and covering an outer circumferential surface of a portion of the dielectric tube facing to at least one tube sheet of the tube sheets (90, 91), the discharge suppressing member being electrically in contact with the metal tube or the tube sheet; wherein the discharge suppressing member is formed by curling the metal plate longer than an outer circumferential length of the dielectric tube into a circular shape so as to have an overlapping portion, and by joining together, in the overlapping portion, a part of the metal plate placed outside and a part of the metal plate placed inside, at a near-end portion of the metal plate placed outside in the overlapping portion; - the discharge suppressing member having on the part of the metal plate placed outside in the overlapping portion, a spring portion stretched in a circumferential direction of the dielectric tube and configured by forming in the metal plate, a plurality of slits that extend in a direction perpendicular to the circumferential direction of the dielectric tube, and wherein among the plurality of slits, there are two slits (172, 173) partly overlapping to each other in their projections toward an end portion in a circumferential direction of the discharge suppressing member. - a hermetically sealed vessel; - two tube sheets (90, 91) each comprising a conductive metal plate having a hole formed therein, which are provided in the hermetically sealed vessel so as to partition its inside into three spaces; - a metal tube provided so as to connect the holes of the two tube sheets (90,91); - a dielectric tube with a metal electrode formed inside thereof, which is held inside the metal tube so that a predetermined gap is given between an outer wall of the dielectric tube and the inner wall of the metal tube; and - an AC power supply for applying an AC voltage between the metal tube and the metal electrode; - the ozone generating apparatus being configured to flow an oxygen-containing source gas from either one of spaces placed at both end sides among the three spaces to the other one of the spaces placed at both end sides, through at least the gap; - to generate ozone by discharging the source gas flowing through the gap while placing the metal tube and the tube sheets (90, 91) at ground potential and placing the metal electrode inside the dielectric tube at high potential; and - to cause cooling by flowing cooling water in a space partitioned by the two tube sheets (90, 91), an outer wall of the metal tube, and an inner wall of the hermetically sealed vessel; and - the ozone generating apparatus further comprising a discharge suppressing member formed of a metal plate and covering an outer circumferential surface of a portion of the dielectric tube facing to at least one tube sheet of the tube sheets (90, 91), the discharge suppressing member being electrically in contact with the metal tube or the tube sheet; - the discharge suppressing member having on the part of the metal plate placed outside in the overlapping portion, a spring portion stretched in a circumferential direction of the dielectric tube and configured by forming in the metal plate, a plurality of slits that extend in a direction perpendicular to the circumferential direction of the dielectric tube, and