An active gas generation apparatus generating active gas obtained by activating source gas supplied to a discharge space, said active gas generation apparatus comprising: a first electrode component (1, 1A, 1B); and a second electrode component (2, 2A, 2B) disposed below said first electrode component, wherein said first electrode component includes a first dielectric electrode (11, 11A, 11B) and a first metal electrode (10, 10A, 10H, 10L) disposed on an upper surface of said first dielectric electrode, said second electrode component includes a second dielectric electrode (21, 21A, 21B) and a second metal electrode (20, 20A, 20H, 20L) disposed on a lower surface of said second dielectric electrode, an AC voltage is applied across said first metal electrode and said second metal electrode, and, in a dielectric space in which said first dielectric electrode and said second dielectric electrode oppose each other, a region in which said first metal electrode and said second metal electrode overlap each other in plan view is included as said discharge space, said second dielectric electrode has at least one gas ejection port (9, 9A, 9B) to externally jet said active gas, and a path from said discharge space to said at least one gas ejection port is defined as an active gas flow path, said active gas generation apparatus further includes an orifice part disposed in said second dielectric electrode itself or below said second dielectric electrode, and having at least one through hole corresponding to said at least one gas ejection port, characterised in that said first electrode component further includes an auxiliary conductive film (12, 12A, 12B) disposed on said upper surface of said first dielectric electrode independently of said first metal electrode, and said auxiliary conductive film is disposed to overlap a portion of said active gas flow path in plan view, and is set to ground potential. a first electrode component (1, 1A, 1B); and a second electrode component (2, 2A, 2B) disposed below said first electrode component, wherein said first electrode component includes a first dielectric electrode (11, 11A, 11B) and a first metal electrode (10, 10A, 10H, 10L) disposed on an upper surface of said first dielectric electrode, said second electrode component includes a second dielectric electrode (21, 21A, 21B) and a second metal electrode (20, 20A, 20H, 20L) disposed on a lower surface of said second dielectric electrode, an AC voltage is applied across said first metal electrode and said second metal electrode, and, in a dielectric space in which said first dielectric electrode and said second dielectric electrode oppose each other, a region in which said first metal electrode and said second metal electrode overlap each other in plan view is included as said discharge space, said second dielectric electrode has at least one gas ejection port (9, 9A, 9B) to externally jet said active gas, and a path from said discharge space to said at least one gas ejection port is defined as an active gas flow path, said active gas generation apparatus further includes an orifice part disposed in said second dielectric electrode itself or below said second dielectric electrode, and having at least one through hole corresponding to said at least one gas ejection port, characterised in that said first electrode component further includes an auxiliary conductive film (12, 12A, 12B) disposed on said upper surface of said first dielectric electrode independently of said first metal electrode, and said auxiliary conductive film is disposed to overlap a portion of said active gas flow path in plan view, and is set to ground potential.