A rotating brush (51) is configured in such a manner that the rotating brush (51) is provided with a shaft (51a) which is configured to be rotatable about the axis thereof and also with a brush section (51b) which is mounted to a part of the outer peripheral surface of the shaft (51a) and that dust caught by an air filter (30) is removed by the brush section (51b). The brush section (52b) of a cleaning brush (52) is configured in such a manner that the dust which adheres to the brush section (51b) is removed when the rotating brush (51) is rotated. The shaft (51a) of the rotating brush (51) is configured so as to cover either one end and/or the other end of the brush section (51b) in the rotational direction.
