The high-voltage electrode 14 can be formed from a foil-like metal. Examples of the high-voltage electrode 14 include a metal foil such as a copper foil and an aluminum foil that are provided with adhesive processing on one side thereof. The high-voltage electrode 14 can also be a sintered body containing conductive metal. The sintered body containing the conductive metal can be formed by printing metal paste on the surface of the dielectric substrate 12. This configuration eliminates the need for using an adhesive when forming the high-voltage electrode 14 on the dielectric substrate 12. The high-voltage electrode 14 may be formed by plating, vapor deposition, or sputtering and thermal spraying. This configuration eliminates the need for using an adhesive when forming the high-voltage electrode on the dielectric substrate. The high-voltage electrode 14 and the dielectric substrate 12 is preferably adhered to each other as closely as possible, and their connection interface preferably has no air layer. The air layer may generate discharge inside the space, which in turn generates radicals, degrading the electrode. Hence, the high-voltage electrode 14 and the dielectric substrate 12 are preferably formed to adhere to each other on the order of micrometers at their connection interface. The thickness of the high-voltage electrode 14 is very thin compared to that of the dielectric substrate 12. The high-voltage electrode 14 being formed from the thin metal makes any expansion of the metal to be absorbed by the thin metal, causing the effect of the expansion to be negligible on the dielectric substrate 12. Furthermore, in the conventional method, the thickness of the dielectric substrate 12 needs to be increased to avoid damage to the ceramics. In contrast, the present embodiment enables the thickness of the dielectric substrate to be thin, which reduces dielectric loss in the dielectric layer, and increases the effect of introducing energy into the gas, making it possible for the efficient plasma generation. Generally, this configuration is capable of providing an efficient device with a small amount of material, which is beneficial in terms of resources and environment.