To provide a switch for safely and completely shutting off large DC current at a high voltage without fusing or damaging a contact with a small-sized constitution irrespective of a manual operation type, a relay type or a thermal protector type.

The manual operation type switch 1 for shutting off a DC current has a positive temperature coefficient 9 connected as a nonlinear resistance element in parallel with a contact circuit formed of a first fixed contact 5-1 and a first movable contact 4-1 via a connector 3-1, an upper surface electrode 9-1 and a lower surface electrode 9-2, connecting wire 6a, and a movable part 6. First, the first fixed contact 5-1 and the first movable contact 4-1 are opened but the positive temperature coefficient 9 is connected in parallel so that the contact circuit is closed, the surge current is hardly generated. A shut-off current flows through the positive temperature coefficient 9. After a peak current passes due to the drop of the resistance value caused by instantaneously heating of the positive temperature coefficient 9, a power source voltage is restored by the rise in the resistance value of the positive temperature coefficient 9, and thereafter since a second fixed contact 5-2 and a second movable contact 4-2 are opened, thereby the current is completely shut off.