Disclosed is a discharge device (40) for generating a streamer discharge from the tip of a discharge electrode (41) towards a counter electrode (42). The discharge electrode (41) in the shape of a wire or rod is disposed substantially parallel to the counter electrode (42), whereby, even when the tip of the discharge electrode (41) becomes worn out, the shape of the tip of the discharge electrode (41) remains unchanged and the distance between the discharge electrode (41) and the counter electrode (42) remains unchanged. As a result, even when the tip of the discharge electrode (41) becomes worn out, the streamer discharge stability will not fall.
