A front loading washing machine including a housing; a water reservoir installed in the housing for containing washing water; a spin tub provided in the water reservoir to hold laundry to be washed, the spin tub having an annular recess and rotating with respect to a horizontal axis of the washing machine; and at least one balancer installed in the annular recess of the spin tub, the balancer having a plastic annular shaped housing that defines a closed internal space.