To automatically transmit character information to be transmitted from a master station at a given time and upon receiving character information data from external equipment in a municipalities disaster prevention broadcasting system comprising a control station, the master station and a plurality of terminal stations, performs character information transmission from the control station or the master station, and displays the character information at a terminal station.

The character information which is transmitted by a letter information transmission device and its transmission time are stored and the character information is automatically transmitted at a given time. Also, the device has an interface for the character information data transmitted to and received from the external equipment by the character information transmission device and automatically transmits the character information upon receiving the character information data.