The present invention relates to a sanding tool, and more particularly to a sanding tool for smoothing a repair surface. A sanding tool according to the invention is for sanding a surface of a target plane to be repaired into a predetermined condition, which is composed of a base plate, on the front face side of which sandpaper can be stretched, and movable base plates being disposed bendably on opposite sides of the base plate and on each front face side of the movable base plate, sandpaper can be stretched. The movable base plates are resiliently energized in a direction wherein the surface of the base plate becomes flush with the surfaces of the movable base plates, respectively. According to a sanding tool of the present invention, a surface to be repaired can be sanded by an easy operation to obtain a good finish, even if an operator is not skilled.