There is provided a distance measuring apparatus having system flexibility by varying a distance measuring range and a distance measuring resolution according to an environment and circumstance. The apparatus includes a reference pulse generator and a delay pulse generator capable of controlling frequencies of a reference pulse and a delay pulse and duty ratios of the reference pulse and the delay pulse. The reference pulse generator and the delay pulse generator include a programmable clock generation unit generating a clock of a frequency determined by a frequency control signal and a duty ratio control unit controlling a duty ratio of the clock generated by the programmable clock generation unit.