A delay locked loop circuit includes a clock buffering block to generate first and second internal clocks corresponding to first and second edges of a source clock in response to a clock buffering control signal, respectively, wherein generation of the second internal clock is controlled by a duty correcting operation terminating signal and a delay locking signal, a delay locking block to compare phases of the first and second internal clocks with those of first and second feedback clocks, respectively, to enable the delay locking signal according to a delay locking and delay the first and second internal clocks as many as times corresponding to the comparison results, respectively, thereby outputting first and second delay locking clocks, a duty correcting block to mix phases of the first and second delay locking clocks, and a first signal generating block to generate the duty correcting operation terminating signal.