The present invention relates to a dishwasher that can save wash water for cleaning and a method of controlling the dishwasher. A method of controlling a dishwasher according to an exemplary embodiment of the present invention is a method of controlling a dishwasher having a circulation channel through which wash water is supplied to wash a plurality of arms by a wash pump after collecting the wash water, sprayed in to a tub from the plurality of wash arms, in a sump, and the method includes: performing a first water-supplying for supplying a predetermined amount of wash water into the dishwasher by opening a water supply valve; performing a first washing where the plurality of wash arms spray the wash water into the tub to be circulated by operating the wash pump; performing a first draining for saving recycling wash water as much as the volume of the circulation channel and draining the rest of the wash water to the outside of the dishwasher by operating the wash pump and the drain pump; and performing a second water-supplying for supplying the amount of wash water except the amount of the recycling wash water from a predetermined amount of wash water into the dishwasher by opening the water supply valve.