A fan includes a motor, an impeller and a heat dissipating structure. The impeller includes a hub and a plurality of first blades. The hub receives the motor, and the hub comprises at least a heat dissipating hole. The first blades are disposed around the hub. The heat dissipating structure is disposed outside the hub. The heat dissipating structure includes a baffle and at least a second blade extending from the baffle and disposed corresponding to the heat dissipating hole.