Electronic toll collection system

The present invention intends to provide an electronic toll collection system for suppressing multi-path. For this end, the electronic toll collection system automatically collects tolls by establishing wireless communication between a roadside antenna 23 of a toll gate and a vehicle unit 33 installed in a traveling vehicle. It features a road-to-vehicle wireless communication zone of the tollgate covered with a structure 22 including radio wave absorbing material. The inner surface is preferably made from a radio wave absorbing member 11 including a mixture 13 of magnetic material and synthetic rubber. The roadside antenna 23 is installed inside the structure 22, thereby enabling the roadside antenna 23 to wireless communicate only with ETC vehicles traveling in the structure 22 and preventing multi-path between the roadside antenna 23 and vehicles traveling outside the structure 22 (or outside the communication zone).