Provided is a clock timing adjustment device for adjusting a time difference of clocks and a delta-sigma modulator. The clock timing adjustment device includes a power detection unit and a timing adjustment unit. The power detection unit receives input signals which are generated using pairs of first and second clocks having a plurality of clock time differences and respectively correspond to the clock time differences, detects powers of the input signals, and outputs a control signal corresponding to a clock time difference where the power is minimized. The timing adjustment unit receives a reference clock and the control signal and outputs the first and second clocks having the clock time difference where the power is minimized from the reference clock according to the control signal.