An inner surface finishing tool enables machining of a workpiece made of a material machinable with a relatively large burnishing amount while reducing deformation at the opening of the workpiece or deterioration of its geometrical tolerance during machining of the inner peripheral surface. The tool includes a mandrel rotatable relative to the workpiece and includes a polygonal member, and a frame that is cylindrical and fitted onto the mandrel in a rotatable manner and has an axis extending in an axial direction of the mandrel and holds a plurality of first rollers and a plurality of second rollers rollable on an outer peripheral surface of the mandrel. The polygonal member rotates the plurality of second rollers to move inward and outward in a radial direction of the frame.