A plate with a passage and the like capable of shortening a process time than a previous one and of suppressing leakage from or contamination to the passage are provided. The particular metal oxide and the thickness of the metal oxide layer are selected so that hydrofluoric acid generated by the fuel cell continuously etches away the layer at a predetermined rate so that a surface of the layer is free of contaminants over the entire life of the fuel cell. The second circuit may be configured to generate a plurality of output signals in response to the intermediate signal.