PURPOSE: To simplify the white balance adjustment by generating a primary color signal from a white video signal, comparing one of primary color signals as a reference with other primary color signals and displaying the result of coincidence.

CONSTITUTION: This adjustment circuit is constituted of amplifiers 1, 11, 21 amplifying R, G, B primary color signals with variable gains for each signal, adjustment operation sections 2, 12, 22 for the amplifiers, a picture tube 3 displaying a picture, a 1st A/D converter section 4, a 2nd A/D converter section 14 and a 3rd A/D converter section 24 converting an output signal of the amplifiers into a digital signal, a 1st adjustment section 5 and a 2nd adjustment section 25 adjusting a level of a digital signal for comparison reference, a 1st comparator section 7 comparing an output of the 1st A/D converter section 4 with an output of the 1st adjustment section 5, a 2nd comparator section 17 comparing an output of the 3rd A/D converter section 4 with an output of the 2nd adjustment section 25, a 1st display section 8 displaying the result of comparison of the 1st comparator section 7 and a 2nd display section 18 displaying the result of comparison of the 2nd comparator section 17.