The blowout outlet 30 is formed at the second end of the gas channel 25 to blow out the gas that has flown through the gas channel 25 and the plasma that has been generated in the gas channel 25. In the first embodiment, the width of the groove 22 (gas channel 25) is uniform from the first end to the second end, and the blowout outlet 30 has also the same width as that of the groove 22 (gas channel 25). This ensures that the flow of gas that has flown into the gas channel 25 fails to be disturbed and that the gas evenly flows out of the blowout outlet 30. This has been confirmed with simulation by the present inventors. However, the present invention is not limited to this example, and the width of the blowout outlet 30 may be adjusted as necessary. For example, setting the width of the blowout outlet 30 to be narrower than the width of the second end of the gas channel 25 enables the plasma to jet with high pressure. Setting the width of the blowout outlet 30 to be narrow to suit the discharging portion can generate a dense and uniform plasma. Setting the width of the blowout outlet 30 to be wider than the width of the second end of the gas channel 25 is capable of ejecting plasma with a wide width.

Examples of the gas supplied to the gas channel 25 (gas delivered from the gas delivery device 40) as starting gas at a time of starting include at least one type of gas selected from the group consisting of He, Ne, and Ar. Examples of the gas capable of generating desired active species as a gas for generating plasma after the plasma has been generated, include at least one type of gas selected from the group consisting of hydrogen, oxygen, water, and nitrogen.