To avoid increase of cost of the whole device while avoiding such situation that ions are not normally generated in an ion generation element.

The ion generation element 30 in which electrodes 43, 44 are formed on both faces of an upper plate 42 of a dielectric substance board 40 is provided in the air supply unit 2a to supply ions generated by applying a driving voltage between the electrodes 43 and 44 into the inside of a room together with air. A scraping-off means 51 for scraping off a floating substance in the air adhered to the electrode 43 is provided. Preferably, a wind mill 50 rotated by stream of air supplied into the inside of the room is provided, and the scraping-off means 51 is carried on the wind mill 50.