PURPOSE: To operate an inserting processing without dividing the color signal of a digital video signal into color difference signals R-Y and B-Y.

CONSTITUTION: An input signal inputted from an input terminal 1 is transmitted to a delay apparatus a switcher 4. The out of the delay apparatus transmitted to a delay 3 and the switcher 4. The outputs of the delay apparatus 3 and the switcher 4 are respectively transmitted to a storage part 6 and 7, and written according to a write-in address outputted from a write-in address generator 8. Signals read from the storage parts 6 and 7 according to a read-out address outputted from a read-out address generator 9 are transmitted to a delay apparatus 13 and a subtracter 12 of an interpolation circuit. The output of the subtracter 12 is multiplied by an interpolation coefficient outputted from a read only memory 17 by a multiplier 14. The output of the multiplier 14 is added to the output of the delay apparatus 13 by an adder 18, and outputted from an output terminal 19. Thus, a digital special effect device whose circuit constitution is.