PURPOSE: To improve the horizontal moires in particular by attaining the improvement of moires with no deterioration of the image quality.

CONSTITUTION: A moire correcting circuit 4 produces a sine wave having the frequency of an odd multiple of 1/2 fV (vertical scan frequency) synchronously with the fV received from a vertical deflecting circuit 2 and superimposes the sine wave on the horizontal synchronizing signal of a horizontal phase circuit contained in a horizontal deflection circuit 3. The horizontally deflected current flowing to a CRT is slightly modulated based on the sine wave. Thus the position of an image is varied on the CRT 1. As a result, the moire stripes caused in the horizontal direction can be visually erased.