To obtain excellent silencing performance by a sound absorbing system of a sound absorbing material and a resonance system of an air layer, and prevent scattering of the sound absorbing material.

This silencer is provided with a housing 4, an inner pipe 1 having plural small holes 2 formed and penetrating the inside of the housing, a silencing material 3 provided on the outer periphery of the inner pipe along a fixed range, and an air layer 5 disposed between the silencing material and the housing. The silencing material is formed by winding inorganic long fiber round the outer periphery of the inner pipe. At least a part of the silencing material comes into contact with the housing. The cross section of the housing is noncircular. The inorganic long fiber is wound round the outer periphery of the inner pipe having small holes, and then accommodated in the housing having a circular cross section. After that, the housing is deformed to a noncircular section by pressing, thereby forming the air layer between the sound absorbing material and the housing.