A receiver includes: a first amplifier for amplifying an input signal and outputting an output signal; a clock generator for generating a clock signal corresponding to a period of the output signal; a judger for outputting a first logical value or a second logical value in accordance with a phase lead or phase lag which has been occurred at a crossing point of the positive-phase signal and the negative-phase signal of the output signal upon rising or falling the clock signal; a detector for outputting a difference value between a time for which the judgment signal has the first logical value and a time for which the judgment signal has the second logical value; and an adjustor for adjusting reference voltages of a positive-phase signal and a negative-phase signal of the input signal in accordance with the difference value output from the detector.