An improved jitter detecting method and an appara­tus thereof, for detecting a jitter generated in a repro­duced video signal of a VTR or video disc wherein a frequency-modulated carrier of a video signal is recorded by synchronizing the leading edge of a sync signal with the phase of the forefront carrier of a constant frequency carrier train corresponding to a sync tip for every horizontal period at the time of a frequency-modulation, and from the reproduced frequency-modulated carrier the phase-reset constant frequency carrier train is abstracted as a reference burst signal, thereby to be capable of removing a time-base error by detecting a specifie zero-crossing timing of the abtracted carrier burst through a bandpass filter based on the tailing edge of a frequency-modulated sync signal at the reproduction.