A cooling air supply apparatus of a refrigerator that is capable of uniformly supplying cooling air to all food received in a receiving box is disclosed. The refrigerator includes a refrigerating compartment and a freezing compartment for storing food at low temperature, a barrier for partitioning the refrigerating compartment and the freezing compartment from each other, and a receiving box mounted in the refrigerating compartment for receiving food. The cooling air supply apparatus includes a communication port formed through the barrier for guiding cooling air from the freezing compartment into the refrigerating compartment, and a hollow box-shaped cover mounted at the top part of the receiving box. The cover is provided at one side thereof with an introduction port, which communicates with the communication port. The cover is provided at the lower part thereof with at least one cooling air supplying hole, which communicates with the interior of the receiving box.