This paper deals with the noise evaluation and noise reduction of a reciprocating air-compressor. The reciprocating air-compressor is widely used in the small and medium sized industrial firms, many employees exposed and irritated by their noise in the workplace. Thus, appropriate noise control actions should be taken to prevent hearing loss due to the its noise exposure. Lead-wrapping techniques are employed to identify the contribution of principal noise sources which are generally known to be motor, belts, suction valves, discharge valves, moving parts, and flow-induced noise caused by edges or discontinuities along the flow path including expansions, contractions, junctions and bends. As a result, the main noise sources of the air-compressor are categorized by the suction and discharge noise, valve noise, and compressed air tank noise. Based on the investigations, mufflers are designed to reduce both the suction and discharge noise and the compressed-air tank noise. Instead of the conventional valve plate, polyethylene resin is used the reduction of valve impact noise. In addition, attempts are made to reduce the valve noise propagation to the cylinder head and the compressor tank by using the insulation casings. As a result of the countermeasure plans, a noise reduction up to 10dB(A) could be achieved for the air-compressor.