A washing machine having a steam generating device for directly heating wash water to generate optimum steam, and a method for controlling the same are provided. The method includes sensing a temperature of the steam generating device; controlling water supply means according to the temperature of the steam generating device such that wash water is supplied to the steam generating device; and controlling a quantity of wash water supplied from the water supply means. Further, the steam is supplied so as to rapidly soak laundry, thereby shortening overall washing time, and reducing energy consumption. Also, the steam is sprayed onto the laundry to provide sterilizing effects. Soaking effects of the laundry are improved, as well, so as to increase washing efficiency and eliminate wrinkling.