To provide a polishing tool having smoothing efficiency of waviness and reducing the deterioration of a workpiece surface shape when polishing an aspheric optical element with large curvature variation.

This polishing tool has such a constitution as to form a closed space 5 of a thin-wall bag-shaped elastic body 2 capable of following the aspheric shape, fill the inside of the closed space 5 with fine powdery particles 3, divide the closed space with a filter 4 having a mesh finer than the diameter of the fine powdery particle 3, form a channel 8 capable of decompressing and pressurizing the closed space inner space 5 in a space having no fine powder 3 of the divided closed space 5, when the bag-shaped elastic body 2 which pushes a tool toward the aspheric shape to form a closed space 2 with the fine particles 3 freely flowing in the closed space 5, follows the aspheric shape, to operate an external pump and decompress the inside of the closed space 5. This polishing tool comprising the film 2 and the fine powdery particles 3 hardened by the decompression executes torsional movement at a fine angle to polish the aspheric shape.