A discharge electrode (70) is made of a metal material, and includes a plate-like electrode support plate (71) and a plurality of discharge sections (73, 74) arranged along, and supported at, a side edge portion of the electrode support plate (71) so as to be opposed to a counter electrode (60). An insulating member (41) includes a support (47) which supports a middle region (71a) of the electrode support plate (71) between two outermost discharge sections (73a, 74a) of the plurality of discharge sections (73, 74).
