PURPOSE: To easily prevent short-circuit and others caused due to oxidation of surface of an electrode terminal and migration between electrode terminals during the operation under high temperature and humidity conditions, by coating a surface of the electrode terminal with an Au layer.

CONSTITUTION: Many filamentary conductive electrodes 3' and 4' formed by e.g., Ag layer are arranged at standard intervals on inner surface of glass substrates 1 and 2. Dielectric layers 5 and 6 are attached to surface of the discharge electrodes 3' and 4'. Surface of electrode terminals 3 and 4 formed by the Ag layer exposed and guided to end parts of the glass substrates 1 and 2 is covered by an Au plating layer 9.