To provide a method for cleaning an air supply passage and a device therefor in which the air supply passage can be assuredly and clearly cleaned and its cleaning operation is simple and easy.

After ducts 10A and 10B are charged with a cleaning and wiping body C, air supplied from a fan 5 or a string shaped traction member 31 connected to the cleaning and wiping body C is pulled, so that the cleaning and wiping body C abutting on the inner wall surfaces of the ducts 10A and 10B is moved to one direction or to both directions. A cleaning solvent B with which the cleaning and wiping body C is impregnated or a cleaning solvent B supplied from a solvent source adheres to the inner wall surfaces of the ducts 10A 10A ad 10B, hence stain adhering to the inner parts of the ducts 10A and 10B is cleaned and removed under the gynergetic effect of the cleaning solvent B and the cleaning and wiping body C. Thus, the stain adhering to the inner parts of the ducts 10A and 10B can be assuredly and clearly cleaned and removed, a cleaning operation can be easily and simply performed and an operation efficiency can be improved.