To provide an electric breaking device for earthquakes that is easily mounted on an arbitrary molded-case circuit breaker and that prevents an occurrence of a fire when power supply is resumed after an earthquake.

A main unit 11 comprises breaking engaging members 16a to 16j that are mountable and detachable at positions corresponding to each molded-case circuit breaker 4a to 4j. A weight 17 is protrusively provided at the bottom end of the main unit 11. The weight 17 has weight that drops each of the circuit breakers 4a to 4j from the upper position to the lower position when weight is applied by making the engaging members 16a to 16j engage each of the circuit breakers 4a to 4j. A guide member 12 that can guide the main unit 11 is mounted on a distribution board 1 for a housing in such a way that each of the circuit breakers 4a to 4j is dropped from the upper position to the lower position, engaged by the engaging members 16a to 16j. A support member 13 supports the main unit 11 with the weight 17 in such a way that the main unit 11 drops along the guide member 12 by vibrations of a prescribed strength or larger.