PURPOSE: To uniformalize air blown into a room by sucking the air into a dust collection element and a suction chamber by means of a single suction multivane centrifugal fan so that the air is blown into the room from a blowoff chamber, a blowoff passage and a blowoff port.

CONSTITUTION: In a casing 1 including a suction port 11 and a blowoff port 12; a dust collection element 2 and a single suction multivane centrifugal fan 3 with a vertical shaft are provided. A box-like partition wall 4 provided apart from a surrounding wall 14 of the casing 1 forms a suction chamber 5 of the fan 3 on the secondary side of the element 2, wherein the upper part of the chamber 5 communicates with the fan 3 through a suction port 32. Further, blowoff chamber 6 is formed between the wall 4 and a top plate 13, while a blowoff passage 7 leading from the chamber 6 to blowoff ports 12 is formed outside the chamber 5. As a result, air blown from the ports 12 provided on the periphery of the casing into the room can be uniformalized.