To prevent the occurrence of a band or a damping factor caused by variation in frequency conversion gain of an oscillation circuit in a phase synchronization circuit.

While putting together and supplying an initial current Iini and a frequency control current Iosci for oscillations at respective frequencies to a current control oscillation unit 101A by using decision reference frequencies f1 and f2, a gain characteristic information acquiring unit 107A measures information (Iout_2) on the difference between oscillation control signals Iosci_1 and Iosci_2 of the decision frequencies f1 and f2 prescribing a frequency conversion gain Kcco of the current control oscillation unit 101A in actual operation, and stores data thereof in a frequency comparison result holding unit 172_2. In phase synchronizing operation, a control current Icpcnt based upon data D(f2) of the frequency comparison result fcomp stored in the frequency comparison result holding unit 172_2 is used to control a driver 104Z to cancel the variance in frequency conversion gain Kcco.