The erasion level appending range of a file is instructed. According to this instruction, the erasion level is set. When this setting range does not agree with the cell unit of the current cell, the current cell is divided to set a sequence of divided cells. Playback management information of each of the divided cells and current cell is re-created, and erasion level information is appended to playback management information of the divided cell that belongs to the appending range.