To efficiently reduce contour and stair-step artifacts.A video encoding device includes an inverse quantization means for inversely quantizing a quantization index to obtain a quantization representative value, an inverse frequency transformation means for inversely converting the quantization representative value obtained by the inverse quantization means to obtain a reconstructed image block, and a noise inject means for determining a pseudorandom noise injecting position based on information on extension of the reconstructed image block and injecting a pseudorandom noise into an image at the pseudorandom noise injecting position.