The invention relates to a voltage-controlled piezoelectric oscillator capable of linear frequency control. In a conventional frequency control using a unidirectional voltage control of a variable capacitance diode, there is a limitation in a correction amount for obtaining a linearity. A voltage controlled piezoelectric oscillator comprises, as its variable capacitance means, a first variable capacitance diode; a first capacitor connected in parallel to the first variable capacitance diode; a second variable capacitance diode; a second capacitor inserted between the cathode of the first variable capacitance diode and the anode of the second variable capacitance diode; and a third capacitor inserted between the anode of the first variable capacitance diode and the cathode of the second variable capacitance diode. The opposite polarities of the external control voltage are applied to the respective ones of the first and second variable capacitance diodes.