A washing machine is provided. An inner drum (1) of the washing machine is a container closed after an opening is fastened by a door cover (4). A plurality of lifting ribs (8) are arranged on the side wall of the inner drum (1). The lifting ribs (8) are hollow inside and communicate with the interior of the inner drum (1). At least one drainage port (10) communicating with the hollow portions of the lifting ribs (8) is formed in the side wall of the inner drum (1). A sealing valve (9) located inside each lifting rib (8) is arranged at each drainage port (10). During the high-speed rotation of the inner drum (1), valve bodies (92) of the sealing valves (9) move along a radial center direction of the inner drum (1) under the action of a centrifugal force, so as to open the drainage ports (10) formed in the side wall of the inner drum (1). Through the above arrangement, the drainage ports (10) are hidden inside the lifting ribs (8) of the inner drum (1), so that the objective of discharging water flow in the inner drum (1) to the outside from the hidden drainage ports (10) is achieved. Meanwhile, the sealing valves (9) are arranged at the drainage ports (10) to achieve the objective that the centrifugal force during the high-speed rotation of the inner drum (1) is used to correspondingly control valve cores of the sealing valves (9) such that the drainage ports (10) are automatically opened for corresponding drainage from the inner drum (1). Through the above arrangement, clothes in the washing process are only in contact with washing water in the sealed inner drum (1).