An electrode structure includes a metallic electrode having a configuration of a bending cylinder and having a plurality of members disposed successively in an axial direction of the electrode and mutually connected with adjacent member(s); a case for installing the metallic electrode and one end of a lead wire for electrification therein; and an insulating member which is positioned between the case and the electrode and which the case from the electrode. An electric heater includes a housing, a honeycomb structure installed in the housing, and the electrode structure for electrifying the honeycomb structure. The electrode structure exhibits excellent composability, waterproof ability, and gas sealability.