A dishwasher may include a tub configured to accommodate one or more items to be washed, a spray arm rotatably mounted to the tub, and configured to spray water onto the one or more items to be washed, a sump disposed at a bottom surface of the tub and configured to store water and to supply stored water to the spray arm, a fixed gear unit fixed to the tub with gear teeth arranged along an outer circumferential surface of the fixed gear unit, a rotary gear unit rotatably mounted on the spray arm and configured to engage the gear teeth of the fixed gear unit, and a link member connected to the rotary gear unit and the spray arm, where the spray arm may include, a main arm with a pair of arms, and a pair of auxiliary arms rotatably connected to the main arm.