The present invention aims to provide a novel Agrobacterium-mediated method for producing a transformed plant.In the transformation method of the present invention, one of the features is to comprise (i) a coculture step for culturing an Agrobacterium-inoculated plant tissue with a coculture medium containing 3,6-dichloro-o-anisic acid, 4-amino-3,5,6-trichloropicolinic acid and/or 2,4,5-trichlorophenoxyacetic acid, and (ii) a regeneration step for culturing the tissue obtained in (i) with a regeneration medium containing a selective drug to thereby induce regeneration, wherein said method does not comprise, between the coculture step and the regeneration step, any selection step for culturing the cocultured tissue with an auxin-containing medium to select a transformant by drug selection.
