A washing machine with a liquid additive supply device capable of sensing an amount of liquid additive contained therein. A buoyancy body and a sensing unit are disposed in a reservoir tank of the liquid additive supply device. The vertical position and therefore the distance between the buoyancy body and a sensing unit vary with the surface level of liquid additive in the reservoir tank due to buoyancy effect. The buoyancy body may include a magnetic body and the sensing unit can detect the intensity of the magnetic body. The surface level of the liquid additive is too low, the sensing unit can generate a signal indicative of liquid additive shortage.
