To obtain a desired wind volume while decreasing the rotation speed of the impeller in order to achieve quieter operation by increasing the wind blowing efficiency of the centrifugal blower itself in the centrifugal blower for a fertilization device which transports manure by the force of wind to a desired place to manure.

A number of main vanes 40 are disposed in regular pitches to an impeller 29 installed inside a casing 31, extending from near the center of rotation to the outer circumference in the circumferential direction. Moreover, supplementary vanes 41 disposed only near the outer circumference of the impeller 29 are provided between main vanes 40. The supplementary vanes 41 provided between the main vanes 40 at predetermined pitches or at circumferentially irregular pitches can lower the peak value of pressure fluctuation in a regular cycle which corresponds to the number of main vanes 40. This makes it possible to generate little offensive noises to the ear.