The present invention relates to a cooling fan, comprising: a cylindrical hub coupled to a driving shaft of a driving motor; a plurality of main rotational blades radially arranged on and coupled to an outer circumference of the hub; and a plurality of auxiliary rotational blades arranged between each of the main rotational blades and coupled to the outer circumference of the hub, wherein each main rotational blade includes a removal part of which a part near the hub side is removed, and the size of each auxiliary rotational blade is smaller than the size of each main rotational blade.
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