A drum type washing machine includes a housing; a rotary drum having a substantially horizontal or slanted rotational axis; a water tub, suspended in the housing, for accommodating therein the rotary drum; a controller for controlling an operation of the washing machine; and a displacement detecting unit disposed between the water tub and a base portion of the housing, for detecting displacement of the water tub. The displacement detecting unit has a primary coil wound around a bobbin; a first secondary coil without overlapping the primary coil and a second secondary coil overlapping the primary coil, the first and the second secondary coils being wound coaxially with the primary coil; and a magnetic body vertically movable inside the bobbin corresponding to a displacement of the water tub.