PURPOSE: To provide a vibration generator and a fail-safe pressure sensor which can generate a highly energetic output with the aid of the vibration generator when a pressure is lower than as specified.

CONSTITUTION: An electromagnet 7 which is AC-excited by a signal generating circuit 8 is prepared on a base 1 to vibrate a cantilever spring 13 on which a permanent magnet 14 and a vibrator 15 are provided, thereby constituting a vibration generator to convert the vibration of the spring 13 into an electric signal through the vibrator 15. Further, the base 1 of the generator is provided with a pressure sensitive pipe 5 of which a closed end 5B is shifted by the pressure, a contact spring 16 interlocked with the end 5B of the pipe 5, and so on, and when there is a high pressure inside the pipe 5, the spring 16 is brought into contact with a free end of the spring 13 based on the shift of the end 5B and is tied thereto so as to stop the vibration of the spring 13. Thus, when the pressure exists, the low-energetic output is generated, while the highly energetic output is generated when the pressure does not exist.