A displacement detection portion is provided in a lever portion of a cantilever or between the lever portion and a main body portion. The displacement detection portion is provided by laminating two conductor electrodes to sandwich an insulating portion. A thickness of the insulating portion (electrode interval) is set to a value capable of detecting a variation in tunnel current due to a change in electrode interval which corresponds to a displacement of the lever portion while a predetermined voltage is applied. When the lever portion is slightly displaced, the interval between the conductor electrodes changes. Therefore, the displacement may be detected as the variation in tunnel current at high resolution with sensitivity of an exponential multiple of the change in interval.