Disclosed is a method of transforming monocotyledons which necessitates only a short period from the transformation to the regeneration of a whole plant as compared with the conventional methods, thus reducing the frequency of occurrence of mutants, and can be generally applied to the plants for which any system of regenerating the whole plants from protoplasts has not been established, and in which the material to be used can be readily prepared without any particular apparatuses. The present invention provides a method for transforming monocotyledons comprising transforming scutellum of an immature embryo of a monocotyledon with a bacterium belonging to genus Agrobacterium containing a desired gene, which immature embryo has not been subjected to a dedifferentiation treatment, to obtain a transformant.