To cause no damage on a washed/polished face, to prevent a device from breakage in the case of a dropping collision, and to hardly sink the device in the water by arranging a damping float with built-in removable buoyancy tank and/or capacity variable tank in the outer circumference of a waterproof case storing a power source, a switch, a pump and the like.

A rotary brush device 2 is provided with a commercial alternating current power source electricity receiving unit or a secondary battery power source 5, a switch, a motor, a speed reduction gear 8, and a rotary brush 20 mounted freely removably to a speed reduction gear output shaft, and these components are stored/in a waterproof sealed case. The rotary brush device 2 is also provided with a pneumatic/hydraulic pump and a damping float 3 having a capacity variable tank 23 surrounding the rotary brush device 2 outer circumferential part freely removably or a buoyancy tank with built-in suction hose with a tip part plumb. In addition, by means of the pneumatic/hydraulic pump, air is fed to the inside of the damping float 3, and/or a liquid detergent or water inside the damping float 3 is sucked outward so as to feed the liquid detergent or water to the rotary brush 20.