PURPOSE: To suppress a current of power supply at the time of insertion and to preclude the adverse influence of a noise by equipping a 2nd contact piece with a resistor which has a specific resistance value when a contact and a network are connected and decreases in resistance value to zero after the end of sliding.

CONSTITUTION: A 2nd terminal piece 7 when made to abut on the contact 6 is connected through the resistor 8, which is excluded from a connection part by sliding after abutting. Therefore, when a power source is connected through the 2nd terminal piece 7, the current of the power supply is suppressed first by the resistance of the resistor 8 and supplied gradually to slide the contact 6 to the 1st terminal piece 4, so that the resistance of the resistor 8 is removed by final positioning. Consequently, a large current of the power supply is prevented from flowing at the moment of the insertion to eliminate malfunction.