In the electronic watermark detection device, an electronic watermark detection unit receives input of a DCT coefficient and a picture start from a preprocessing unit to detect an electronic watermark inserted into image data and indicative of copyright information or the like, a detection result adjustment unit receives input of a picture start from the preprocessing unit and input of a detector result and a detector interruption from the electronic watermark detection unit to count the number of pictures, as well as generating and outputting a detection interruption according to the detection result, and an interruption processing unit receives input of a detection result and a detection interruption from the detection result adjustment unit to generate an interruption signal according to a system, as well as outputting the detection result.