Provided are a device and method for detecting watermarks in content carrying watermarks. One method for watermark detection according to the present invention comprises the steps of: extracting the label of a frequency component of the content; generating a bit sequence by making bit values correspond on the basis of changes in the label being extracted; checking correlation while shifting the phase of the band-spreading code (pn sequence) with respect to the generated bit sequence; and checking the amount of phase shift in the band-spreading code at times when the correlation checked in this way falls into the category of autocorrelation, and then determining a bit group having a value corresponding to the amount of phase shift checked in this manner. The bit group determined in this way constitutes part of watermark data.