Graphene is formed with a practically uniform thickness on an uneven object. The object is immersed in a graphene oxide solution, and then taken out of the solution and dried; alternatively, the object and an electrode are immersed therein and voltage is applied between the electrode and the object used as an anode. Graphene oxide is negatively charged, and thus is drawn to and deposited on a surface of the object, with a practically uniform thickness. After that, the object is heated in vacuum or a reducing atmosphere, so that the graphene oxide is reduced to be graphene. In this manner, a graphene layer with a practically uniform thickness can be formed even on a surface of the uneven object.