Positive pressure air supply device and biosafety cabinet

The invention provides a positive pressure air supply device and a biosafety cabinet. The positive pressure air supply device comprises a fan, a filter, a cloth bag and a mounting frame, wherein an air outlet is formed in the mounting frame; the cloth bag is provided with an air inlet connecting opening and an air outlet connecting opening, wherein the air inlet connecting opening is connected with an outlet of the fan, and the air outlet connecting opening is connected with an air outlet; and the air outlet is covered by the filter. The cloth bag is used as an air passage, and is made of cloth, so that the cloth bag has good buffering capacity, air flows generated by the fan are transmitted in the cloth bag, the cloth bag can well buffer impact of the air flows to an inner wall of the cloth bag, and air resistance is effectively reduced; and besides, the cloth bag has good flexibility, the air flows can obtain uniform air pressure during being transmitted in the cloth bag, so that down air flows in the cloth