PURPOSE: To prevent a surge from being given to a submarine cable system by connecting a feeding path to a submarine ground with a feeding path switching means and providing a resistor to absorb the surge so as to absorb the surge at the time of switching the feeding path.

CONSTITUTION: Contacts r1-r4 in the initial state are connected as shown in figure and contact r3b, r4a are opened. Moreover, a submarine branching device H is located close to a terminal station A. At first a voltage is gradually increased or decreased to increase a current to both terminal stations A, B. Since terminal stations A-C are all at the same potential when the current is on the brinking state of a sensing current of a relay RL1, a voltage close to the voltage of the terminal station A is being stored in the submarine cable around the submarine branching device H. When the current between the terminal stations A, B reaches the sensing current of the relay RL1, the contact r1 is switched to the position shown in broken lines. In this case, the charge stored in the submarine cable at the terminal station C is going to flow through a sea water ground G, but the surge is absorbed by the resistor R and no surge is exerted to a repeater around the submarine branching device.