The purpose of the present invention is to reduce the risk of contamination in a clean air device in which a safety cabinet and clean booths are coupled. To achieve this, a clean air device in which a cabinet and clean booths are coupled, is configured such that the cabinet is equipped with: a work space which is formed on the inner side of a front shutter; and a circulation path which is formed from the lower surface, side surfaces, rear surface of the work space, and an outside portion of the cabinet so as to exhaust the air flowing into the work space. Pass boxes connected to the clean booths are provided to a portion of the side surfaces of the work space. Each of the pass boxes is formed by a pass box coupling inner surface, the outside of which has a space formed by a pass box coupling outer surface. The space communicates with the circulation path. The bottom of the pass box coupling outer surface is provided with a pass box coupling outer surface slit.