To easily break a feeder line by a temperature rise and vibration in an earthquake, by providing a sensitive element and a control means starting when the sensitive element is turned off.

A breaker is provided with a switch means 30 connected to an AC power source 10 through a coil for contact point pull-out 41 and a diode 61 provided for rectification, the control means 20 turning on the switch means 30 when a breaking cause is detected and the sensitive element 50 which is turned off when the temperature rise and vibration are detected. When an abnormal temperature rise and vibrations by earthquake exist in a regular power feeding state, the sensitive element 50 detects heat and vibration and it is turned off. The control means 20 is started and the switch means 30 energizes the coil for contact point pull-out 41, opens contact points 11A and 11B, and breaks the power feeder line. Thus, the power feeder line can easily be broken by the temperature rise and the vibration by an earthquake in addition to a former breaking function.