To provide an air cleaning method and its device which efficiently remove impurities which cannot be sufficiently removed only by water droplet injection, and supply air to a place requiring highly purified air, such as a clean room.

Mist M of pure water 112 and a particulate adsorbent 113 are injected from the injection nozzle 105 of an air washer 104 into air flowing through an air duct 102, and dust and impurities in the air are caught with the mist M, and impurities which cannot be sufficiently caught with the mist M are caught with the adsorbent 113. The pure water 112 and the adsorbent 113 recovered in a recovery tank 108 are fed to the air washer 104 to be injected again, and the adsorbent 113 in the recovery tank 108 can be regenerated by an adsorbent regenerator 114, which enables the efficient removal of the impurities from the air even with a small amount of the adsorbent 113.