Abstract: The air pressure variation detector comprises a base plate having a through hole or a cavity, a piezoelectric element fixed to the base plate so as to locate above the through hole or the cavity and formed in a strip-like shape having a width narrower than the inside width of the through hole or the cavity, an impedance converter circuit consisting of a field effect type transistor and a leak resistor, and an electrically conductive accomodating container having a vent hole. An output terminal of the piezoelectric element is connected to a gate of the field effect type transistor, and the leak resistor is connected between the gate and a ground terminal of the piezoelectric element. This air pressure variation detector is simple in its composition and can detect with high accuracy slight variations of air pressure in the enaudible region.