A centrifugal fan, in which an expansion angle of a radius of curvature of the outer periphery of a scroll housing from a position angle of a cutoff portion, serving as a suction portion, to a designated portion from the former in the direction of air flow is gradually decreased; and an expansion angle of the radius of curvature of the outer periphery of the scroll housing from the above designated portion to a discharge portion is gradually increased, thereby easily converting the velocity of the discharged fluid to pressure due to the increased dimensions of the discharge region and increasing the flow rate. Further, since noise generated from a cutoff portion of the centrifugal fan of the present invention maintains the same level as that of the conventional centrifugal fan, the centrifugal fan of the present invention has reduced noise at the same flow rate.