A coding distortion removal method is provided for removing coding distortion in an area disposed on both sides of a block boundary between a first block and an adjacent second block in a picture having a plurality of blocks, each block being adaptively coded either as a field structure block, comprising only even field pixels or comprising only odd field pixels, or a frame structure block, comprising odd field pixels and even field pixels. The method includes detecting whether the block boundary between the first block and the adjacent second block is a block boundary between a field structure block and a frame structure block, and performing a coding distortion removal process on the first block and the adjacent second block. The coding distortion removal process includes determining whether coding distortion removal is needed, determining the number of pixels to be processed, and removing coding distortion.