To provide a pattern latent image generating device that is a pattern system capable of setting latent image character strings that are aligned as one group when setting a plurality of character strings for utilizing as a latent image in a pattern, suppresses the overlapping of the character strings of the latent image, and can embed efficient pattern information, and to provide a pattern latent image generation method and a medium in which the pattern latent image generating method is recorded.

There are provided: a means for acquiring the set character string; a means for checking whether there is no overlapping in the set character string; a means for deleting an overlapped character string; and a means for utilizing the result, where the overlapped character string is deleted, for generating a latent image. Further, a means for determining the overlapped character string includes conditions, such as complete search, prefix search, suffix search, included, and non-included.