Washing machine

A washing machine capable of heating wash water in accordance with supply of steam and hot water, while preventing scales from being formed on a heater (32, 80) adapted to generate steam and hot water. The washing machine includes a water tub (11) for containing wash water, a heating tank (31) for containing a predetermined amount of water to generate steam, a heater (32, 80) arranged in relation to the heating tank (31), and adapted to heat the water contained in the heating tank (31), a water supply unit (20) for supplying water into the water tub (11) and the heating tank (31), a steam supply pipe (51) for guiding the steam from the heating tank (31) to the water tub (11), a steam supply valve (52) for opening and closing the steam supply pipe (51), a drainage pipe (61) connected to the heating tank (31), and adapted to drain the water remaining in the heating tank (31) after completion of the generation of steam, and a drainage valve (62) for opening and closing the drainage pipe (61).