To provide a CRT display which reduces moire phenomena generated by interference between a picture signal pattern and a shadow mask pitch without degrading the picture quality.

Picture signals 1 are converted into digital signals by an A/D converter 2 to be stored in a line memory 3 and read out by a line memory 3 by a read-out clock R whose frequency is modulated at a horizontal period so that the picture signals 1 are modulated in the time-axis direction and converted again into the analog signals A by a D/A converter 4. A voltage control oscillator circuit 9 is varied by changing the frequency deviation at a prescribed modulation level so that the relation of the interval between respective dots of the picture signals 1 to the mask pitch is deviated so as to prevent the degradation of the picture quality and reduce the moire.