This washing machine is provided with: a centrifugal separation unit (21) for separating foreign matter contained in wash water in an outer tub (1); a pump (20) for circulating the wash water between the outer tub (1) and the centrifugal separation unit (21); a water channel (19) which connects the outer tub (1), the pump (20) and the centrifugal separation unit (21), and through which the wash water flows; and a control unit (22) for controlling a wash operation. The centrifugal separation unit (21) comprises: a case (21a) through which the wash water in the water channel (19) passes; a hollow rotary drum (21b) positioned in the case (21a)so as to enable rotation; a rotary drum motor (21c) for driving the rotation of the rotary drum (21b); a wash water inlet (21e) which allows the wash water to flow into the rotary drum (21b); and a wash water outlet (21f) which allows the wash water to flow out of the rotary drum (21b). At the start of a wash cycle, before the rotary drum (21b) begins its regular rotation, the control unit (22) vents, from the rotating cylinder (21b), air mixed into the wash water that has entered the rotary drum (21b).