Drum washing machine and method for cleaning tub thereof

A drum washing machine includes a tub and a drum rotatably supported in the tub and implements a control method that allows the tub to be easily cleaned. The method of controlling the washing machine includes supplying washing water during a first water supplying step to the interior of the tub while the drum is rotating at a water-supplying RPM; and executing a first wash step following completion of the first water supply step by accelerating the rotation of the drum from the water-supplying RPM to a first-wash RPM so that a circulatory flow is created in which the washing water falls from the top of opposite ends of the tub while circulating along the inner circumferential surface of the tub due to the rotational power of the drum.