A drum-type washing machine is disclosed which includes a ventilation apparatus that provides an air passage for an inner space of a tub to communicate with an external atmosphere. The ventilation apparatus employs a bubble dissipation device that prevents bubbles generated in the tub from reaching a ventilating bellows and being discharged from a cabinet of the washing machine. The ventilation apparatus includes a ventilating duct formed at an upper part of the tub; a ventilating bellows, one end of which is coupled to an exterior surface of the cabinet and the other end of which is connected to the ventilating duct, to allow a passage of aim the tub to the external atmosphere; and a bubble dissipation device, vertically installed along the air passage of the ventilation apparatus, for preventing bubbles generated in the tub from being discharged from the cabinet. The bubble dissipation device includes a float movably disposed in the ventilation apparatus to travel between a seated stated and a raised state, under a force of a forming air bubble, for blocking the air passage of the ventilating bellows when a bubble is generated and allowing the air of the ventilation apparatus to pass freely when no bubble is generated.