The conventional combination cannot realize an efficient road traffic system as a whole. A transmission system has a plurality of modules installed at different positions along a predetermined road. Each of the plurality of the modules includes a receiving section for receiving an input signal and a transmission section for transmitting an output signal on the basis of the input signal according to a predetermined radio scheme. Each of the plurality of the modules receives and transmits a signal, whereby the whole or part of the information contained in the signal is transmitted along the whole or part of the predetermined road. This transmission system can construct an efficient integrated road traffic system as a whole.