In a direct current cutoff switch1, a PTC 5, which is a non-linear resistor, is parallel connected to a contact circuit composed of a fixed contact 4-2 and a movable contact 8-2 via electrodes 5-1. When the switch is closed, no current flows in the PTC 5 with a prescribed resistance value at 25.degree. C., since voltage between both the electrodes 5-1 is almost "0". When the switch is opened in order to cut off current, the contacts form a closed circuit since the PTC 5 is parallel inserted between the fixed contact 4-2 and the movable contact 8-2. For this reason, it is difficult for surge voltage to occur and an arc hardly occurs between both the contacts. The PTC 5 instantaneously heats due to passing current, reduces the resistance value and passes peak current. Then, the resistance value rises and becomes stable in a high value such that weak current which is negligible at 42V, which is rated voltage. Thus, current is substantially cut off.