There is provided a jitter measuring apparatus for measuring jitter in a signal-under-measurement, having a pulse generator for outputting a pulse signal having a pulse width set in advance corresponding to edges-under-measurement from which the timing jitter is to be measured in the signal-under-measurement, a filter for removing a carrier frequency components of the signal-under-measurement from the pulse signal and a jitter calculator for calculating the jitter in the signal-under-measurement based on the signal outputted out of the filter