To accomplish reduction of noise and improvement of an assembly property while suppressing deterioration in strength as much as possible by using a porous member partially.

In a centrifugal blower, in which multiple blade pieces 3, 3,... are installed between a main plate 1 to which a rotary shaft is pivoted and a shroud 2 provided with a suction port, 4, the main plate 1 and the blade pieces 3, 3,... are constructed of an integrated molded product made of fused synthetic resin. On the other hand, the shroud 2 is constructed of a porous material possessing a sound absorbing function, and the shroud 2 is clamped and fixed by means of a ring member 5 fused to the blade pieces 3, 3,..., so that reduction of noise and improvement of an assembling properly can be accomplished with deterioration of strength suppressed as mush as possible.