PURPOSE: To prevent a small amplitude noise from remaining as a still picture while maintaining a noise decreasing effect by changing a feedback coefficient to big and small at every prescribed field in an area where the difference of video signals between a current field and a preceding field is small.

CONSTITUTION: This is the digital type noise decreasing circuit of a cyclic type using a field correlation, is provided with a field delay circuit 13 and a coefficient multiplier 15D, and fed back to the current field video signal to multiply a difference Sdf of each video signal between the current field and the preceding field by a prescribed feedback coefficient K. In this case, in the area with the small difference, the feedback coefficient is changed to big one Ka and small one Kb at every field. Thus, while maintaining the noise decreasing effect, it is possible to prevent the small amplitude noise from remaining as the still picture.