PURPOSE: To improve productivity, to reduce costs and to miniaturize the oscillator by setting a reference frequency temperature characteristic obtained with averaging the frequency temperature characteristics of plural crystal oscillator, selectively impressing a common compensating voltage to a voltage variable capacity element, and compensating the frequency temperature characteristic of each crystal oscillator.

CONSTITUTION: A temperature compensating circuit 8 is formed by connecting a voltage variable capacity element 9 to the other edge side of each commonly connected crystal oscillator 7, and further providing a compensated voltage generating circuit 11 impressing a compensated voltage through a resistance 10. Further it is set so as to compensable the reference temperature characteristic obtained by averaging the temperature characteristic of each crystal oscillator 7. That is, the compensated voltage from the compensated voltage generating circuit 11 is set so as to be the reverse characteristic to the reference temperature characteristic, and based on the setting, the temperature characteristic of each crystal oscillator is compensated. Consequently a single compensated voltage generating circuit is sufficient, its regulation is facilitated, and the productivity is improved. In addition, since the small number of complents is sufficient, reliability is improved, the costs can be suppressed, and the small size can be maintained.