PURPOSE: To surely pull-in synchronization by providing a bias means, a comparator means and a means generating a kick pulse and using the kick pulse to revise a control voltage of a voltage controlled oscillator to a voltage below a lower limit of a setting range.

CONSTITUTION: An output signal of a loop filter 31 is fed to a comparator means 32, in which the signal is compared with a preset reference value and a signal generated from the means 32 is fed to a level trigger pulse generating means 33. The means 33 generates a kick pulse with a prescribed duration time in response to a high level of an output signal from the means 32. The kick pulse is fed to a control voltage revision means 34 connected between a phase error detection means 21 and the filter 31. Then a control voltage to a voltage controlled oscillator 14 is forcibly changed during the duration time of the kick pulse to allow the voltage controlled oscillator 14 to oscillate an oscillation signal at a lower frequency below a lower limit in a preset oscillated frequency range. Thus, it is not required to provide a complicated triangle oscillator.