PURPOSE: To improve an effective picture element number and to obtain a sharp picture by changing over a changeover switch 4 so as to connect a video input terminal of a television telephone circuit to a video output terminal and outputting a video signal from the video output terminal.

CONSTITUTION: When a power supply for a television telephone circuit 1 and an amplifier circuit 4 is turned off, a changeover switch 6 is thrown to the upper position and a video signal inputted from a video input terminal 2 is outputted from a video output terminal 5. Moreover, when the power supply is turned on, the changeover switch 6 is thrown to the lower position and the video signal is inputted to both the television telephone circuit 1 and the amplifier circuit 4. As a result, after the input video signal is once stored in the television telephone circuit 1, the signal is read as required and extracted from a memory output terminal 3 and the amplified video signal via the amplifier circuit 4 is outputted from the video output terminal 5. In this case, since the valid picture element number of the video signal from the video input terminal 2 is kept, picture quality is maintained.