Disclosed is a axial flow fan of an outdoor unit of an air conditioner. The axial flow fan comprises a hub connected with a rotational shaft of a motor; and at least one blade contacting the hub, wherein the blade has a part from the hub to a predetermined portion of the blade among a whole part from the hub to an outer end of the blade, and the other part from the predetermined portion of the blade to the outer end of the blade, the part being equally applied at a predetermined rake angle, and the other part being raised in a direction of a pressure surface of the blade, and wherein a ratio of an inner diameter and an outer diameter of the axial flow fan is between about 0.35 and about 0.4.