PURPOSE: To efficiently suppress vibration extending from the begining of dehydration to the time of completion of dehydration by providing an energizing means for giving energizing force to an outer tank through a suspension device at the time of dehydrating operation.

CONSTITUTION: A suspension device 9 arranges a metallic spring 35 and a rubber piston 37 in a cylinder 33 whose lower part is sealed hermetically with an enclosed cover 31, and the cylinder 33 is fixed and supported through a bracket 39 by an outer tank. In a pneumatic chamber 43, a control passage 49 allowed to communicate mutually with a communicating hole 47 of the cylinder 33 and having a large passing resistance and a discharge port 51 are provided, and the pneumatic chamber 43 is led to the outside through the control passage 49. Also, in the discharge port 51, a driving motor 55 which is installed in the enclosed cover 31 and becomes an energizing means, and an opening/closing valve 57 controlled so as to be freely openable and closeable by the driving motor 55 are provided. The opening/closing valve 57 controls a damping coefficient by the passing quantity, by which air pressure of the pneumatic chamber 43 passes through the control passage 49 and suppresses vibration by giving a limit to a motion of a hanging bar 7, that is, an outer tank through the piston 37 and the cylinder 33 of the suspension device 9 in accordance with resistance at the time of passing through the control passage 49.