Abstract: The present invention generally relates to a structure of an optical digital pen. In particular, the invention relates to an optical digital pen by use of light scattering which can effectively acquire positional information of a pen tip even when the optical digital pen moves at a tilt on a display panel having a smooth surface. The invention is advantageous in that even when an optical digital pen is used at a tilt on a panel having a smooth surface made of glass or transparent plastic, reflected light for acquiring positional information of a pen tip is sufficiently received. In addition, the optical digital pen has an advantage of being compatibly used with a display panel of an electronic device such as a tablet PC or a laptop computer.