To stably and completely hold a washing rotary tank by providing a vibration proof device for preventing the vibration of the washing rotary tank of a washing machine at the time of moving a car body on the lower part of the washing rotary tank.

The vibration proof device 60 is attached to a trailer truck 1 at the lower part of the washing rotary tank 6b and the vibration proof device 60 is composed of a bracket 60b to which a bearing 60bb is integrally fixed, a screw shaft rod 60d a fixing tool 60b like a stopper nut. In the movement of the trailer truck 1, when a handle 60f is turned and the screw shaft rod 60d is elevated, the washing rotary tank suppression member 60e of the screw shaft rod 60d pushes up the bottom part 6bb of the washing rotary tank 6b and suppresses the movement of a vibration body 60a. Thus, the washing rotary tank 6b is suppressed. Then, by moving the fixing tool 60g to the lower end part of the bearing 60bb and locking it, a suppression state is held.