Abstract: Provided are a microbial power generation device, an electrode for the microbial power generation device, preparing methods of the same, an electric power producing method using microbes and a selective culture method of the microbes used for the electric power producing method capable of improving electric power production capacity and of suppressing power generation cost. In a microbial power generation device (1), microbes (reducing microbes) that reduce graphene oxide are enriched among microbes inhabiting wastewater, slurry, activated sludge and the like. Therefore, the graphene oxide is reduced by the reducing microbes, so the graphene is produced. Electrons produced by the microbes can be transmitted to a negative electrode (14) via the produced graphene. As a result, the electric power production capacity can be improved and the power generation can be performed at a low cost.