Traffic information output device/method and traffic information distribution device/method

A traffic information distribution system includes a distribution device for synthesizing pieces of traffic information supplied from a traffic information center, an output device for outputting pieces of traffic information distributed from the distribution device, and a data communicator that is connected to the output device and that can communicate with the distribution device in a bidirectional manner. The distribution device responds to a request signal transmitted from the output device via the data communicator, effectively synthesizes the pieces of traffic information in consideration not only of a request made by a user, recognizability at the time of output, a state of a map on a display screen and a range of the map, but also of various factors in which actual road conditions are reflected. The pieces of the traffic information that have been synthesized are distributed via the data communicator to the output device.