To provide a device and a method for measuring jitters, capable of measuring jitters for the reproducing signal of disk recording media of various speeds by one device.

This device is comprised of an A/D converter for converting the reproducing signal of a disk recording medium into a digital signal, an equalizer for amplifying the specific frequency component of the digital signal converted and output from the A/D converter, a phase difference generation circuit for generating and outputting a phase difference between timing at which the output signal of the equalizer crosses a predetermined threshold value and a clock, a phase synchronizing circuit for using the phase difference output of the phase difference generation circuit as the phase error input signal of a phase synchronous loop, and applying phase synchronization to reproduce a reading clock, and a standard deviation calculation circuit for calculating standard deviation from the phase difference output of the phase difference generation circuit.