A pressure sensor comprises a movable structure which is movable in accordance with a pressure applied thereto. A piezoelectric transducer is employed against which a pressure is applied when the movable structure is moved. The transducer has opposed electrodes between which a voltage is generated when the transducer is pressed. The capacitance between the opposed electrodes increases with increase of temperature. A dielectric member is arranged in the vicinity of the piezoelectric transducer. The dielectric member has opposed electrodes the capacitance between which decreases with increase of temperature. The piezoelectric transducer and the dielectric member are electrically connected in series.