PURPOSE: To prevent the stopping of a driver for driving a converter by stopping the driving temporarily when a watch is exposed to a low temp. environment.

CONSTITUTION: When the watch is exposed to a low temp. environment, the internal resistance of a battery increases and when the battery voltage drops below the minimum voltage at which an IC is operated, the output of a detecting circuit 3 is inputted to a driving control circuit 6, by which the inputting of the ordinary driving period signal from a frequency dividing circuit 2 to a driving circuit 4 is inhibited. When the ordinary driving period signal is up-counted with an up-down counter, the output state of the pulses for correcting the driving during the driving stoppage period of the circuit 6 is maintained by the output of a coincidence circuit 7. Hence, the driving of the converter is stopped temporarily.