A CRT display apparatus having an FBT amplifying an inputted voltage and outputting the amplified voltage to an anode of a CRT, a vertical regulator to regulate a V-size of a screen, and a vertical deflector to vertically deflect a scanning line, further comprises a brightness change sensor to sense a voltage applied to an input terminal of a secondary induction coil provided in the FBT, and to output a sensed signal to the vertical regulator; and a brightness change compensator to output a compensating value to the vertical regulator based on the voltage applied to the input terminal, a frequency of the scanning line, and a specification size of the screen to compensate a brightness change. With this configuration, a V-size fluctuation due to a brightness change is minimized in the CRT display apparatus.