An air blowing unit of an air conditioner includes a housing to guide suction and discharge of air, a centrifugal fan positioned inside the housing, and a motor to drive the centrifugal fan. The centrifugal fan includes a base coupled to a motor shaft coupled to the motor, a plurality of blades disposed spaced apart from each other in a circumferential direction of the base to guide air introduced in an axial direction of the base to the circumferential direction, a leading edge provided to the blades and arranged close to the motor shaft, a trailing edge provided to the blades and facing in an outer circumferential direction of the base, and at least one first blade of the blades, the leading edge of the first blade being shorter than the leading edge of the other blades.