The high-voltage electrode 14 is connected to the power supply unit 42 at a first end of the high-voltage electrode 14. In the first embodiment, a power introduction section 34 for connecting to the power supply unit 42 is provided on the first end of the high-voltage electrode 14. The method of connecting the power supply unit 42 to the high-voltage electrode 14 at the power introduction section 34 is not limiting as long as they are electrically connected and can withstand the applied voltage. Examples of the method include connection by solder and connection using various connectors such as coaxial connectors. However, since microwaves are not used in the present embodiment, there is no need to use coaxial connectors or coaxial cables with a specified characteristic impedance.

The applied voltage and frequency supplied from the power supply unit 42 suffices to be within a range that enables the plasma generator 10 to generate dielectric barrier discharge. Specifically, the applied voltage supplied from the power supply unit 42 is preferably in a range of 3 kV to 20 kV, and more preferably 10 kV or lower. The frequency of the applied voltage supplied from power supply unit 42 is preferably in a range of 20 kHz to 1000 kHz, and more preferably in a range of 100 kHz to 150 kHz. The reasons for setting an upper limit of 150 kHz are that the frequency is determined with the consideration of the plasma irradiation length of the dielectric barrier plasma generator and that the frequency detected with the noise terminal voltage conformed with the Electromagnetic Compatibility (EMC) standard is 150 kHz or higher.