A method for controlling a washing machine is provided. The method may include determining an amount of laundry in an inner tub, setting a supply water level according to the amount of laundry determined, supplying the water into the inner tub until a water level in an outer tub reaches the supply water level set, setting a rotation speed of a pump motor according to the amount of laundry determined, operating the pump motor at the rotation speed set, and alternatively rotating a pulsator in different directions.