Abstract: A signal quality measuring method and apparatus in which a quality of a signal detected from an RF signal read out from a disk or a communications channel is measured by using eye pattern signals of the detected RF signals. Eye pattern signals representing time change of a waveform of the detected signal are generated and a signal quality value is generated based on an eye depth and/or an eye width measured from the eye pattern signals. A histogram of the eye pattern signals is used to identify a plurality of main level values which are used as a reference value in measuring the signal quality. Accordingly, signal characteristics in a high-density storage medium system or communication system may be accurately represented.