Vibration sensor

The invention relates to a vibration sensor. The vibration sensor is characterized in that the vibration sensor is a seismic acoustic coupling vibration sensor which converts vibration into a sound wave and then converts the sound wave into an electric signal through a microphone and outputs the electric signal; the sensor includes a sealed cavity; the upper surface of the cavity is connected with an elastic diaphragm; the central position of the elastic diaphragm is connected with a counterweight mass body; the counterweight mass body is indirectly connected to the elastic diaphragm through a diaphragm support to achieve the aim of controlling the contact area; the bottom surface of the sealed cavity is sealed by the microphone and a printed circuit board; the microphone directs at the internal part of the sealed cavity; and the sealed cavity is provided with a housing. The vibration sensor solves the technical problem that a former low frequency vibration sensor is large in volume and high in weight and an