A digital watermark detection apparatus includes an extraction unit extracting a specific frequency component signal from an input image signal, a first transformation unit orthogonal-transforming the image signal, a second transformation unit orthogonal-transforming the specific frequency component signal, a combination unit combining first and second transformed image signals from the first and second transformation units, a third transformation unit orthogonal-transforming a combined image signal, an estimation unit estimating embedded watermark information by searching for a peak appearing in a third transformed image signal of the third transformation unit, and a compressor compressing a target signal in amplitude based on a compression characteristic varying according to an amplitude and frequency of the target signal to obtain a compression signal, the target signal formed of at least one of the first transformed image signal, the second transformed image signal and the combined image signal.