A VOB composed of a plurality of VOBUs and Cell information are recorded on an optical disk. Each VOBU includes a plurality of sets of picture data, and the Cell information specifies a reproduction section (Cell). According to a user indication, picture data corresponding to an IN point of a delete section and picture data corresponding to an OUT point of the delete section are specified in the Cell. If the number (j-i-1) of VOBUs present between the ith VOBU including the former picture data and the jth VOBU including the latter picture data is smaller than a predetermined number u, a warning of a data size increase is displayed. If j-i-1 is greater than u, the Cell information is rewritten so that the parts of the Cell preceding and succeeding the delete section become two consecutive Cells, and the (i+s+1)th to (j-t-1)th VOBUs are deleted from the optical disk.