NOVELTY - An electrode terminal (20) is provided with a metal terminal (21) and a corrosion-resistant protective layer (22). The corrosion-resistant protective layer has a layer (A) containing a component (A), one or two layers (X) containing a component (X) and a layer (Y) containing a component (Y). The component (A) contains rare earth element oxide and phosphoric acid or its phosphoric acid salt. The component (X) contains anionic polymer and a crosslinking agent. The component (Y) contains a cationic polymer and a crosslinking agent.    USE - Electrode terminal is used for secondary battery. Uses include but are not limited to lithium ion battery, lithium-polymer battery and lithium ion capacitor used as power supply for mobile telephone and vehicles.    ADVANTAGE - The electrode terminal has improved adhesiveness between laminated package materials for long period of time. The corrosion-resistant protective layer is easily formed.    DETAILED DESCRIPTION - An electrode terminal is held between polyolefin resin layers facing each other by thermal welding under pressure at a peripheral portion of a package configured of a multilayer sheet having at least a polyolefin resin layer on which a metal layer is laminated, in package sealed with at least a positive electrode, a negative electrode and an electrolyte. The electrode terminal is provided with a metal terminal connected to the positive electrode and/or the negative electrode, and a corrosion-resistant protective layer formed on the surface of the metal terminal. The corrosion-resistant protective layer has a layer (A) containing a component (A), one or two layers (X) containing a component (X) and a layer (Y) containing a component (Y). The component (A) contains a rare earth element oxide (a1) and 1-100 pts. wt. phosphoric acid or a phosphoric acid salt (a2) with respect to 100 pts. wt. rare earth element oxide (a1). The component (X) contains anionic polymer and a crosslinking agent for crosslinking the anionic polymer. The component (Y) contains a cationic polymer and a crosslinking agent for crosslinking the cationic polymer.    DESCRIPTION OF DRAWING(S) - The drawing shows the schematic sectional view of electrode terminal.    Electrode terminal (20)    Metal terminal (21)    Corrosion-resistant protective layer (22)    Sealant (23)