PURPOSE: To decrease frequency of arcs generated in the instant of opening an electric switch so as to maintain mutual contact reliability upon contacts in the switch.

CONSTITUTION: An electric switch 1 is constructed in such a manner that a pair of contact segments 3 having their respective contacts 2 may be supported for oscillation by a case 5 via their respective supporting pieces 4, then the contact segments 3 may be pressed against each other by their respective presser bar springs 6 so that the contacts 2 may be brought into contact with each other under predetermined pressure and then the operation of a contact operator member 7 may cause the contacts 2 to be brought in and out of face-to-face contact with each other so as to carry out make-and-break motions. The contact operator member 7 is provided with an inserter 8 made of an insulating material, and also a resistor 9 of large specific resistance. The inserter 8 is then supported by the case 5 in such a manner that it may carry out a rectilinear motion with its head against the head of each of the contact segments 3, and it may therefore be inserted between the contacts 2 and be drawn from therebetween. Although the insertion of the inserter 8 between the contacts 2 causes the contacts 2 to be brought out of contact with each other, the resistor 9 is preset in a position to be brought in slide contact with each of the contacts 2 so that the contacts 2 may be associated electrically with each other, and resistance between the contacts 2 is gradually increased to gradually decrease the volume of an electric current flowing through each of the contacts 2 with the process of inserting the inserter 8 between the contacts 2. This can decrease the frequency of arcs generated both in the instant of bringing the contacts 2 out of contact with each other and in the instant of separating each of the contacts 2 from the resistor 9.