A video signal coding apparatus comprises a divider 102 that divides an input digital video signal into an effective area and an additional area, an effective-area blocking device 103 for dividing the effective area into effective blocks, an effective-area encoder 104 that hight-efficiency-codes the effective blocks to create effective compressed blocks, an additional-area encoder 105 that hight-efficiency-codes the additional area to create additional compressed data, an additional-area blocking device 106 for dividing the additional compressed data into additional compressed blocks each a luminance signal for a plurality of pixels and at least one color difference signal for pixels arranged at the same position as the plurality of pixels, and a substitution device 107 that substitutes the additional compressed blocks for data in the same effective compressed blocks at predetermined positions.