A dishwasher including a washing chamber to wash dishes, a sump concavely formed at a lower portion of the washing chamber to collect water used in washing, a microfilter disposed at the sump to filter out dirt produced when the dishes are washed, and an ultrasonic generator to radiate ultrasonic waves toward the microfilter. Since the microfilter is automatically cleaned by the ultrasonic generator, a user may not need to manually clean the microfilter.