Abstract: An apparatus of material surface observation related to the present invention is a scanning electron microscope which is combined with an accelerator of charged particles. The material surface is activated by irradiation of the charged particles and a surface reaction is induced. Secondary electron in generated by irradiation of the scanning electron beam depending on a shape of the material surface. The secondary electron generated by the irradiation of the scanning electron beam is discriminated from the secondary electrode generated by the irradiation of the charged particles, and only a signal of the secondary electron generated by the irradiation of the scanning electron beam is visualized. Consequently, a reaction process of the material surface which is activated or is reaction-induced by the irradiation of the charged particles can be observed in atomic level with less noise.