PURPOSE: To obtain a character positioning circuit for a video signal capable of surely discriminating a video image and an inserted characters even when a luminance level of the video image of the inserted position and a luminance level of the inserted characters are the same.

CONSTITUTION: A level comparator 4 compares a video signal from a memory 2 with a voltage from an optional voltage generator 5 to provide an output of a character component detection signal. A luminance level detection circuit 6 detects a luminance level of a video signal. An output voltage control circuit 7 controls an output voltage control circuit 7 so as to decrease a voltage outputted from an optional voltage generator 9 when the luminance level of the video signal is high. A switch 8 replaces the video signal received by a terminal B with a voltage received by a terminal A from the optional voltage generator 9 only for a period when the character component detection signal is received to insert a character component into the video signal.