To carry out a processing operation for a work efficiently through a tool by positioning a guide bush inserted into the tool fittingly to the work quickly and smoothly.

This device is provided with a main shaft unit 16 equipping the tool 14 into which the guide bush 12 is inserted fittingly, a first driving structure 20 used to retract the above main shaft unit 16 on the base board 18, a guide bush retaining unit 22 retaining the above guide bush 12, and a second driving structure 24 used to retract the above guide bush retaining unit 22 separately from the above main shaft unit 16.