One of the objectives of a way of the present invention is to form grapheme on an object having a concavo-convex surface in an actually uniform thickness. After the object is impregnated in a graphene oxide solution, the object is taken out from the solution and dried, or the object and an electrode are impregnated, the object is used as an anode and a voltage is applied to between the object and the electrode. Since graphene oxide is negatively charged, the graphene oxide is attracted and attached to the surface of the object in an actually uniform thickness. Then, by heating the object in the vacuum or reducing atmosphere, the graphene oxide is reduced and graphene is obtained. Through the abovementioned steps, even on the surface of an object having the concave-convex surface, graphene of an actually uniform thickness can be formed. For example, a layer of grapheme can be formed on a whisker-shaped silicon surface, so that the silicon is used as an electrical storage device such as a Li-ion secondary battery.