To carry out a centering and edging processing quickly and simply.

This tool is provided with a recessed part 14 having nearly ring shape and V letter section for storing a grinding liquid temporarily and supplying to the centering and edging place of an outer diameter part on the grinding surface of a nearly wheel shape grinding tool 20 for centering the outer diameter part of a lens raw material by rotation. Further, nearly radial slit shape slits 18 communicating with the recessed part 14 are arranged and the grinding liquid supplied from an outside is introduced to the recessed part 14 or the grinding liquid stored in the recessed part 14 temporarily is introduced to the outside.