Disclosed is an axial flow fan capable of achieving reduction of noise while having a high blowing efficiency compared to the power consumption of a motor adapted to drive the axial flow fan. The axial flow fan includes a hub, and a plurality of blades extending radially around the hub. Each blade has a sweep angle varying gradually from a backward angle at a root of the blade connected to the hub to a forward angle at a tip of the blade, while having a flow dispersion region having a plurality of regions where the sweep angle is alternately changed, at a region defined between a backward sweep angle region at the root of the blade and a forward sweep angle region at the tip of the blade. Each blade has a longitudinal cross section curved to have a wave structure between the root of the blade and the tip of the blade. The axial flow fan may further include a fan band connecting tips of the blades. The axial flow fan achieves reduction of blowing noise by receiving air in a dispersed state at the leading edge of each blade, discharging air in a dispersed state at the trailing edge of each blade, and offsetting turbulent flows of air by virtue of the wave-shaped longitudinal cross-sectional structure of each blade.