A semiconductor substrate; a cantilever which is formed on the semiconductor substrate so as to face the semiconductor substrate with an air layer therebetween, the cantilever being made from an electrically conductive material or a semiconductor material, and the cantilever being mechanically movable; a photodiode which is formed so as to be connected in parallel to a capacitance that is constituted from the cantilever and the semiconductor substrate, and the photodiode being formed between an anchor portion which is a portion of the cantilever and the semiconductor substrate; and a power source which supplies voltage via a resistance on a side of the cantilever which is a connection point of a parallel circuit including both the capacitance and the photodiode so as to be backward bias to the photodiode, are included.