PURPOSE: To obtain a phase locked loop oscillator circuit with a small phase noise.

CONSTITUTION: First and second thermisters compensating fluctuation of an AC voltage component in a phase comparison output signal 30 with respect to a temperature change are provide in a loop circuit 4 of the phase locked loop oscillator circuit. Then the 1st and 2nd thermisters divides the AC voltage component of the phase comparison output signal 30 and a control signal from the voltage dividing point is led to a voltage controlled oscillator 1. Since the temperature fluctuation in the loop is suppressed by the 1st and 2nd thermisters, the phase locked loop oscillator circuit with a small phase noise is realized without increasing the hardware with small power consumption.