PURPOSE: To provide a bolt detaching/attaching device that is able to set a driver in a bolt and remove the bolt therefrom so surely in making the bolt be self-supporting at the time of clamping start and loosening termination.

CONSTITUTION: In a bolt detaching/attaching device 1 made up of a driver 6 fittable in a head part 4 of a bolt 3 connecting a jig 2 and a work and a wrench hole 4a of this head part 4 and a holding means of a robot hand 5 or the like holding the bolt 3, the holding means is constituted so as to make the bolt 3 so as to be rotated and driven as far as a specified angle around an axis X of the bolt in keeping it held intact at each time of clamping start and loosening termination.