A discharge unit (20) is provided with: a discharge electrode (70)； a counter electrode (60) which is opposed to the discharge electrode (70)； and an insulation member (41) having a surface which is continuous from the discharge electrode (70) to the counter electrode (60). A wall portion (90) which is configured to suppress contaminants from adhering to the surface of the insulation member (41) is provided on one side with respect to a discharge region formed by the discharge electrode (70).
