In an electric discharge device (40) performing streamer discharge from the top of a discharge electrode (41) toward an opposing electrode (42), the discharge electrode (41) with a liner or bar-like shape is placed substantially parallel to the opposing electrode (42). The structure results that the shape of the top of the discharge electrode (41) does not change even if the top wears and the distance between the discharge electrode (41) and the opposing electrode (42) also does not change. This prevents stability of streamer discharge from lowering even if the top of the discharge electrode (41) wears.