PURPOSE: To endure any great variation in load by decelerating jet air running out from moving blades of a fan toward an axis of the fan due to cut-off of the external face of a motor-accomodated case for wide pass of air.

CONSTITUTION: Suction ports 21, 22 of a nozzle 23 is directed in parallel with a dust arresting case 17. Once a power source switch is thrown to run a motor 11, air including dust is suck up from a suction port 21 or 22, filtered by a filter 31, and absorbed into a fan 4 from an air suction port 18 in a partition plate 16. Air current having been powered outwards at an angle by the moving blades 13 is guided in the direction of axial-flow by a diffuser 3 and fed out into open air through an air blast nozzle 8 on a rear cover 7. Wide pass of air by cutting off the external face of a motor-accomodated case 2 decelerates jet air running out from moving blades 13 of the fan toward an axis of it so that the diffuser gains higher efficiency.