To prevent removal of a screw at a fastening place by a screw.

Parts of a head 5, a nut 2, and a locknut 8 of a fastening place of a bolt 1 and the nut 2 are covered using removal preventing materials 10 and 20 for screw, thereby disabling usage of a tool such as a spanner. Cover members 11 and 21 are mounted using pins 12 and 22, and idle even when the members are turned from the outside. For pulling out the pins 12 and 22 of which shaft parts 16 and 26 are pressed into prepared holes 13 and 23 formed in the bolt 1, a dedicated tool is required. The fastening place can be removed only by pulling the pins 12 and 22.