A casing, including an inlet through which air can flow in and outlets through which air can flow out, is internally provided with: an air passage through which the inlet and the outlets are connected to each other; and an ion generation device for discharging ions into the air passage. The casing has an inclined wind guide surface and an attachment surface that forms an acute angle with the wind guide surface. The inlet is provided in a region of the wind guide surface, the distance of which from the attachment surface is shorter, the first outlet is provided in a region of the wind guide surface, the distance of which from the attachment surface is longer, and the second outlet is provided in a region of the casing, extending to the attachment surface from an end of the wind guide surface at which the first outlet is provided.