To provide a vibration sensor which is not limited to the usable range, with simplified wiring, capable of alleviating the effects of signal transmittance noise, capable of high-occuracy reliable measurement and of measuring the degree of vacuum.

The vibration sensor comprises an optical fiber 7; a vibrator body 1 provided at the one side of the optical fiber and the direction of the amplitude of the vibration is arranged so that it coincides with the optical axis of the optical fiber; a light source 14 arranged at the other side of the optical fiber; a light source control device 16 for controlling the light from the light source; a light detection means 18 for detecting the emission light from the optical fiber. The vibration body is excited by intensity modulating the light from the light source by the light source control device, and the light from the light source, reflected by the vibrating body, is made to emit from the other end and is detected by the light detection means, and the displacement caused by the excitation is made measurable.