To change the direction of water flowing toward a painted surface so as to flow toward the center side of a hood, a water deflecting member is provided that extends toward the center side of the hood while extending toward the painted surface as seen in a state where automatic wet sanding is performed. Thus, water bouncing off the painted surface is less likely to scatter over a wide area of the painted surface, and sanding dust is also less likely to scatter over a wide area of the painted surface. As a result, it is possible to eliminate the need for the troublesome task of wiping off sanding dust remaining on the painted surface, and to achieve a quality finish on the painted surface.