As has been described above, the inducing method for regenerating plants from PLBs of orchids in accordance with the present invention is successful in achieving a higher frequency of chromosome doubling, and trending an increase of frequency of chromosome doubling according to the PLB generations (i.e. the number of physical cutting). Advantageously, the polyploid plants obtained from the method of the present invention is highly stable and may not be specifically deteriorated when increasing the culturing time such that the method of the present invention is suitable for orchid polyploidy breeding including hybridization, induced mutation, and new breed developing and improving.