Abstract: In a method of superimposing data of a character (mark) on video data, the superimposed video data being subjected to a data compression processing for extracting video data within each of blocks from one frame of the superimposed video data and for data-compressing the extracted video data, the blocks forming one frame, the each block including a predetermined number of two-dimensionally arranged pixels of the superimposed video data, a position of the character superimposed on the video data with respect to a lump of the blocks, where the character is to be imposed, is determined such that the number of blocks over which the character spreads is minimized when a size and a shape of the character or the mark are unchanged.