PURPOSE: To prevent connection failure when a cord wire is connected.

CONSTITUTION: In order to connect a cord wire 4, a groove 2a having width smaller than a diameter of a conductor 5 of the cord wire 4 and depth deeper than a coating layer 6 of the cord wire 4 is arranged in the tip part of contact metal 2. When the contact metal 2 is calked, the tip part of the contact metal 2 passes penetratingly through the coating layer 6 of the cord wire 4, and is brought into contact with the conductor 5 of the cord wire 4. In this case, the tip part of the contact metal 2 is introduced to the center of the cord wire 4 by the groove 2a arranged in the tip part of the contact metal 2.