A digital watermark embedding apparatus divides data to be watermarked into a plurality of data areas on the basis of data characteristics, in time series, or on the basis of user selection and performs digital watermark embedding in which different algorithms are applied to the separate data areas. Unlike schemes that embed digital watermarks using an algorithm that is uniform with all data areas, a digital watermark can be embedded in accordance with each data area of an image. When the algorithm is selected in accordance with user input, the embedding algorithm can be selected in accordance with the characteristics of the human vision or auditory sense. Image/audio quality control and detection performance improvement are thus made possible, and deterioration in data quality can be prevented.