In order to realize road-road communications, a roadside device is provided with an MS function unit and a BS function unit that have a termination function of a signal. In a case of performing road-road communications, any of plural roadside devices can function as a BS, and others as an MS. In a wireless communication system that only enables wireless communications between MS and BS, road-road communication can be performed. In order to realize vehicle-vehicle communication, an in-vehicle device has the BS function unit and the MS function unit having a termination function of the signal and performs the same operations as the road-road communication. In road-vehicle communication, any of the roadside devices can function as the BS, and other roadside devices and in-vehicle devices are operated as the MS.