1. A toll collection system for determining soundness thereof, comprising:a roadside antenna which wirelessly communicates with an on-board device mounted in a vehicle;
a communication processing unit for carrying out communication processing based on predetermined communication specifications with the on-board device via the roadside antenna;
a communication control unit for acquiring results of communication processing from the communication processing unit and creating information for toll collection with regard to the on-board device; and
a toll collection processing unit for accepting an input of the information for toll collection from the communication control unit and carrying out toll collection processing based on this information for the toll collection,
wherein, in any of a communication pair of the roadside antenna and the communication processing unit, a communication pair of the communication processing unit and the communication control unit, and a communication pair of the communication control unit and the toll collection processing unit,
when a first component, which is one part configuring the communication pair, accepts the input of a predetermined confirmation signal, the first component outputs a predetermined response signal, and
a second component, which is another part configuring the communication pair, outputs the confirmation signal to the first component and determines whether the first component is operating normally based on whether the input of the response signal has been accepted, and
a number of passing vehicles per unit time changes in accordance with a time span, a radio wave receiving soundness determination unit can apply the determination reference time suitable for the number of passing vehicles and determine a soundness.