PURPOSE: To eliminate the necessity of an input terminal exclusive for a blanking signal by fetching the blanking signal for character display, etc., by using a primary color signal input terminal for character display, etc.

CONSTITUTION: First-third amplifiers 34-36, to which primary color signals are impressed from first-third primary color signal input terminals 4-6, are not operated when the primary color signal is less than a prescribed value, and linear amplification is executed at more than the prescribed value. The blanking signal from an external part is added from a terminal 28 to the third primary color signal input terminal 6. When the voltage of the input terminal is less than a prescribed value and within a prescribed range, first-third switches 10-12 are changed over by the output of a comparator 32 and the output signals of the first-third amplifiers 34 and 36 are selected. Thus, when forming a circuit to an IC, the necessity of one external fitting pin for fetching the blanking signal can be eliminated.