To provide a switch which safely shuts off a large DC current at a high voltage without fusing or damaging a contact with a small configuration.

A DC current cut-off switch 1 has a PTC 5 connected as a nonlinear resistance element in parallel with a contact circuit formed of a fixed contact 4-2 and a movable contact 8-2 via an electrode 5-1. A voltage between both the electrodes 5 and 1 is substantially "0" at the PTC 5 having a predetermined resistance value at 25°C as a reference when the switch is closed, and current does not flow. When the switch is opened to shut off the current between the contacts, the contact section becomes a switching passage via the PTC 5 connected in parallel between the fixed contact 4-2 and the movable contacts8-2 so that a surge current hardly occurs, and an arc hardly occurs between both the opened contacts. The PTC 5 is heated instantaneously by the passing current to lower its resistance value. After a peak current flows, the resistance value is raised, the PTC 5 is stabilized at a high resistance value for passing an infinitesimal current of the degree to be ignored at 42V of a rated voltage, and the current is substantially shut off.