A rack structure which is capable of improving heat-dissipating efficiency thereof within a limited space, and a communication apparatus which is capable of enhancing cooling efficiency by applying the rack structure thereto. In the rack structure of the communication apparatus, the air used for cooling printed circuit boards within a lower shelf and thereby increased in temperature is cooled by causing the same to flow through the heat-dissipating duct on a lateral side and is then used again for cooling printed circuit boards within an upper shelf. This makes it possible to increase the heat-dissipating efficiency of the communication apparatus to thereby improve the cooling performance thereof. As a consequence, the necessity of increasing the number of cooling fans or increasing the size of fans becomes small, and the cooling performance of the communication apparatus can be maintained within a limited installation space. Further, the necessity of increasing the rotational speed of fans and the like becomes small, and it is possible to avoid the problem of noise and the like.