PURPOSE: To obtain a pattern plate having a characteristic appearance resembling the wing of a large brown cicada, being clean and giving the viewer a feeling of contact with nature by using as a vein body obtained by specially processing a natural plant leaf to remove the mesophyll therefrom, as a main body of a pattern.

CONSTITUTION: A plant leaf is immersed in a solution of an alkali metal hydroxide, such as sodium hydroxide, for an appropriate period of time. Then, the leaf is washed in pressurized water to remove the mesophyll therefrom, followed by drying to obtain a vein body. The back side of the vein body is stuck to an upper surface of a transparent synthetic resin sheet blank by an adhesive, and is pressed against the upper surface by a roller. The face side of the vein body is then coated with a thin film of a transparent synthetic resin coating material to obtain a desired pattern body.