A digital watermarking apparatus for embedding a data in an index color image data, wherein the data is configured by an arrangement of a first data and a second data, and the apparatus has: an allocating unit for allocating the data to values of positions of a color lookup table included in the index color image data; and an adjusting unit for adjusting a value of the color lookup table to which the first data is allocated, to an odd number, and adjusting a value of the color lookup table to which the second data is allocated, to an even number.