The present invention can detect watermark information from motion picture of various scanning methods and various picture sizes without causing increase of a memory capacity.A watermark information detection apparatus 1 converts encoded watermarked motion picture 4 into standard motion picture 5 having the smallest data size among the assumed kinds of motion picture. Further, the watermark information detection apparatus 1 scales a standard coordination system that is utilized for specifying embedding locations of a watermark pattern. Then, with respect to each field of the standard motion picture 5, watermark information is detected from predetermined locations specified in the scaled standard coordinate system by the watermark pattern.