A terminal structure to be assembled in a terminal slot is integrally formed by pressing a metal plate having first and second surfaces. The terminal structure includes a fixing portion and an elastic arm. The first surface of the fixing portion is fixed in the slot and is wider. The arm is connected to the fixing portion. Over 70% of the first surface of the arm are disposed on the same plane and the first surface of the arm has a curved shape. The first surface of the arm is narrower than the first surface of the fixing portion. An angle smaller than 30 degrees is formed between the first surfaces of the arm and the fixing portion. A top end of the arm exceeds a top end of the fixing portion, and is formed with a movable contact.