To provide an earthquake detecting device capable of detecting a seismic intensity level of earthquakes in a stepwise fashion.

In the earthquake detecting device, a plurality of electrodes connected to a resistor prepared in a plurality of rudder-like forms are arranged in a case the center of which is depressed in a ground direction. Because the metal balls moving inside of case shunt two of the electrodes according to vibration of earthquakes, variation of resistance can be obtained corresponding to the seismic intensity of earthquakes.