Disclosed herein is a drum washing machine which is capable of lifting clothes to a predetermined height and then dropping the lifted clothes so that the clothes can be washed by means of friction and impact. The drum washing machine is capable of heating wash water and spraying the heated wash water into a tub and a drum of the washing machine in a phase of high-temperature and high-pressure steam, thereby rapidly soaking clothes in the wash water, improving sterilizing and washing efficiencies of the drum washing machine, and saving wash water and electric energy.