PURPOSE: To make it possible to achieve fine adjustment of pace acceleration and deceleration quickly and correctly, by changing DUTY of output signal of a voltage control circuit, which controls an oscillation circuit, in accordance with selected frequency division output.

CONSTITUTION: The ON period of a transistor 12 of a voltage control circuit 3 is changed through NAND gates G9WG11, an AND gate G8, transmission gates G5 and G6, inverter gates G3, G4 and G7, and an NOR gate G2, etc. in accordance with combination of prescribed frequency division outputs from a frequency division circuit 2 in accordance with selection operation and the period, during which an oscillator 1 being controlled by constant voltage is controlled by a power source voltage VDD, is changed. Oscillation frequency of the oscillator 1 is finely adjusted in order of 0.1ppm, etc. in accordance with variation of DUTY of this control voltage, and therefore, fine adjustment of acceleration and deceleration of pace is able to be achieved simply, rapidly and correctly.