In a terminal structure, at least one pair of left and right clamp pieces are formed in a terminal in which an electrode is slide-inserted. The left and right clamp pieces elastically press the electrode from both right and left sides when the electrode is inserted in the terminal. A contact piece is formed on at least one of left and right sides of the terminal, and is separated in the slide-insertion direction by a slit from a clamp piece-formed portion where the clamp piece is formed. The clamp piece is elastically deformed to contact the contact piece when the electrode is inserted in the terminal.