PURPOSE: To provide a protective tool for preferably preventing a high tension bolt temporarily fastened and a nut attached thereto from being exposed to wind and rain, and being easily attached thereto.

CONSTITUTION: A protective tool is consisting of an elastic cap 10 to cover a washer 2 attached to a high tension bolt 1 for fixing a material to be clamped, a nut 3, and a bolt part projected from the nut 3, and the cap 10 is attached in a predetermined position by bringing the opening part 10a of the cap 10 in pressure contact with the nut 3 accompanying the elastic deformation of the opening part 10a.