In a relaying apparatus, a label information controller generates and transmits label information including at least one of communication medium information on communication media for use in communication with other apparatuses and communication cost information on communication costs that are generated when communication is performed via the relaying apparatus. In a communication apparatus, a route controller receives the label information, creates a list of routes for use in communication with a communication counterpart, and detects a communication route through which communication is to be performed from the list. The route controller creates a list of all routes including, out of relaying apparatuses, relaying apparatuses which enable communication with a counterpart apparatus using a communication medium which the communication apparatus has, and based on the communication cost information included in the label information, detects a communication route which is lowest in communication costs from the list.