Abstract: A phase lock loop system includes: a phase detecting circuit which operates on the basis of a signal waveform; a current output circuit for generating a current value from a phase difference detected by the phase detecting circuit; a filter which is constructed by only a resistor in a phase locked state by a synchronizing signal and by a capacitor and the resistor upon phase following state; and a voltage controlled oscillator for controlling an oscillation frequency by a voltage output of the filter. The phase lock loop system operates as a primary phase lock loop circuit in the phase locked state by the synchronizing signal and operates as a secondary phase lock loop circuit upon phase following state.