A method of embedding digital watermark information b.sub.1 b.sub.n (2.ltoreq.n) in image data. The image data is divided into a plurality of areas S each consisting of M.times.N (1.ltoreq.M, N) pixels. A plurality of areas G each consisting of P.times.Q (1.ltoreq.P, Q) of the areas S are defined. Each of the areas S constituting each area G is allocated to some one of: areas T.sub.1 T.sub.n in which said digital watermark information b.sub.1 b.sub.n is respectively embedded and areas H.sub.1 H.sub.m (1.ltoreq.m) in which information is not embedded. One or more areas T and one or more areas H are located in a predetermined arrangement in each area G. And, the plurality of areas G are located in a predetermined rule.