CENTRIFUGAL BLOWER

PROBLEM TO BE SOLVED: To reduce the generation of noise, improve the fan efficiency, and reduce the power consumption in a centrifugal blower used in ventilating blowing apparatuses. SOLUTION: In a centrifugal fan 1 in which the shroud-suction opening diameter Dsi of a shroud 3 is 0.60 to 0.85 compared to the fan-outside diameter D of the centrifugal fan 1, the shroud-outer peripheral part 7 positioned at discharge side 5 of the centrifugal fan 1 is inclined to the suction side 6 of the centrifugal fan 1, and the ventilation passage area of any circumferential cross- section Si is larger than the ventilation passage area of a blade-inlet circumferential cross-section S1 in the position in which a blade-inflow part 9 of a shroud- inside peripheral part 8 intersects the shroud 3, the discharge flow 15 of the centrifugal fan 1 is allowed to be directed in the direction of discharge ports 14 of a blower body 10, the discharge speed of the discharge flow from the shroud-outer peripheral part 7 of the centrifugal fan 1 is allowed to be reduced, and thus collisions of the discharge flow with the side wall 16 of the frame of the blower body 10 can be reduced, turbulence in a case body 17 can be reduced to reduce the generation of noise, and the fan efficiency can be improved.