To provide a vibration detector compactly mounted on a part of a circuit board and having an advantage in downsizing and cost reduction without malfunction to detect not vibration but sound.

The vibration detector includes: supporting to fix a chip-like magnet 2 on the tip of an elastic plate body 3 so as to fix the other tip of the elastic plate body 3 on the circuit board 4; assembling a magnetic sensor 1 for detecting a magnetic field on the circuit board 4 so as to be positioned at a near side of the magnet 2; using a Hall element in the magnet sensor 1, for example; forming the elastic plate body 3 of a thin plate member so as to be formed of a film-like flexible substrate, for example; being vibrated by accompanying vibration of the circuit board 4 fixing one end of the elastic plate body 3 since the magnet 2 is supported on the elastic plate body 3 so as to change the magnetic field due to the magnet 2 in response to vibration; and indicating variation of output of the magnetic sensor 1 in response to change of the magnetic field since the magnetic sensor 1 is arranged on the near side of the magnet 2 so as to quantatively detect the size of vibration.