A phase comparator includes: first and second detecting units for detecting an amplitude value of a clock signal at falling timing or rising timing of a data signal; an edge comparing unit for identifying as to whether the first detecting unit detects an amplitude value under a rising state or a falling state to output a first identification result, and for identifying as to whether the second detecting unit detects an amplitude value under a rising state or a falling state to output a second identification result; first and second polarity inverting units for inverting a polarity of output of the first and second detecting units; and a signal selecting unit for selecting one of output values of the first and second polarity inverting units in response to a polarity of the data signal to output the selected output value.