To execute assembly or disassembly work easily and economically by the use of a light noise eliminating panel having high noise insulating performance even in a low frequency area, by surrounding the circumference of a blower with the noise eliminating panel in which a plurality of sound absorbing materials are polymerized.

A noise eliminating panel 5 in which a plurality of sound absorbing materials are polymerized, is arranged to be suspended from the lower surface of a ceiling slab 20 so as to surround the circumference of an axial flow fan 4 while taking in consideration balance between a column 2a and a beam 2b in the ceiling. This noise eliminating panel 5 is so formed that glass wool is arranged on both sides of a two-layer gypsum plaster board arranged in a central cross section, zinc steel plates are arranged on both sides of this glass wool, and many small holes are formed on a side composing the inner wall of a silencer 1. Hereby, in a job site or in a factory, this silencer 1 can be manufactured easily and economically in a desired shape.