PURPOSE: To provide a clean washing machine capable of comfortable washing.

CONSTITUTION: In a washing machine having a washing tub 1 for housing clothes to wash, a water supplying means for supplying washing water (washing water and rinsing water) to the washing tub 1, a stirring means for stirring the washing water; a draining means for draining the washing water; and a spinning means for extracting the washing water from the clothes, a liquid is injected from a injection hole provided on the washing tub 1 or from an injection bar provided in the inner part of the washing tub, or the washing tub is ultrasonically vibrated by an ultrasonic oscillator provided adjacent to the washing tub, whereby the washing tub is cleaned.