PROBLEM TO BE SOLVED: To increase the amount of active species generation.SOLUTION: An active species generation unit comprises: a discharge electrode 17 whose front end side is inserted into a case and a semi-conductive part 18 disposed in a substantially vertical direction to the front end side of the discharge electrode 17 in the vicinity of the front end side of the discharge electrode 17. The semi-conductive part 18 is constituted of a ceramic insulating substrate 16, and a semi-conductive coating body provided on a surface of the discharge electrode 17 front end side of the insulating substrate 16. A hole part 21 is provided to the insulating substrate 16 opposed to the front end side of the discharge electrode 17, and a power supply connector 19 is provided in the vicinity of an outer periphery of the insulating substrate 16. An opening edge part of the semi-conductive coating body is protruded toward the discharge electrode 17 front end side in the hole part 21. The protruded part forms an R-plane 31 covering the discharge electrode 17 side of the hole part 21 end surface of the insulating substrate 16. Voltage from a power supply part 20 is applied to the power supply connector 19 and the discharge electrode 17 to generate an active species by corona discharge.
