PURPOSE: To secure the high accuracy of an electronic timepiece, by selective using a plurality of constant voltage circuits different in temp. dependency so as to match the same with characteristics of a crystal vibrator.

CONSTITUTION: The power source terminal of a crystal oscillator circuit 1 is connected to a constant current circuit 3 controlled by a constant circuit 2 while a circuit 21 having no temp. dependence and circuits 22, 23 respectively having positive and negative temp. dependences are provided to the circuit 2. In addition, in order to obtain temp. dependence of oscillation frequency a switch SW8 for selecting the constant voltage circuit operable from the outside is provided and the circuit 21 is selected by SW8 to measure the temp. dependence of oscillation frequency while temp. characteristics inherent to a crystal vibrator is compensated on the basis of the measured result and the constant voltage circuit for flattening temp. characteristics is selected and used.