Provided in the invention is an earthquake alarm device comprising a metallic conduit arranged at a surface layer. A fiber is arranged in the metallic conduit; a laser device is arranged at the top end of the metallic conduit; and alarm device is connected with the laser device electrically. A laser transmitter, a laser receiver, and a path operation circuit are arranged inside the laser device. According to the invention, alarming can be carried out before spreading of seismic force waves to the surface layer. The device has high practicability.