There are disposed on a printed substrate a crystal resonator as a piezoelectric resonator, an oscillation circuit, a plurality of surface mount heaters and a temperature controlling circuit for controlling a heating temperature of the heaters. A case of the piezoelectric resonator and a lead terminal of the piezoelectric resonator are heated respectively at the same time by individually separate heaters for the purpose of heating the piezoelectric resonator, the oscillation circuit and the temperature controlling circuit at the same time. Accordingly, it is possible to provide a piezo-oscillator excellent in low power consumption and compactness.