A communication module-cooling structure includes a main body section to be cooled by a cooling mechanism, and a heat sink including a cooling receiving section including partition walls and slit-shaped receiving spaces defined by the partition walls. The receiving spaces of the cooling receiving section receive communication modules, and each of the communication modules includes a substrate mounted with a communication circuit component thereon and first and second sidewalls which sandwich the substrate therebetween in a thickness direction of the substrate. At least one of the first and second sidewalls of each of the communication modules is in surface contact with an inner surface of each of the receiving spaces.