PURPOSE: To send an additional signal without revision of the stipulation of the Radio Wave Act by transmitting the additional signal by selecting a cycle number of a color burst signal based on the additional signal.

CONSTITUTION: Signals Y, I, Q are converted into signals Y, I, Q of interlaced scanning structure by switches 14, 15, 16 and time expansion circuits 17, 18, 19. The signals Y, I, Q are converted into a TV signal of the NTSC system by an NTSC encoder 20. A burst replacement circuit 21 replaces a color burst signal added by the NTSC encoder 20 into a color burst signal whose cycle number is decided. A TV signal in which the replacement is finished is fed to an output terminal 22 as a transmission signal. The replacement use color burst signal is outputted from color burst generating circuits 23-26. The four color burst signals are selected alternatively by a selector 27 based on the additional signal and the selected signal is fed to the circuit 21.