Principle of electron holography and a new method for producing the electrostatio field specimen are presented. Some dielectric particles supported by a thin carbon film, for example, polystarene latex spheres, 0.31 m in diameter, will become a charged body during the observation in electron microscope because of electrostatic accumulation. Obviously, under the electron beam, the spheres of radius r, acquire a stationary positive charge Q and the resulting field can be simply modelled by that of point charge Q. With the field model, the electrostatic field distribution were observed and the sizes of the charged objects are determined by electron holography.