To provide a bolt and a fastening tool therefor, by which attaching/detaching operation by a non-authorized person is difficult.

A bolt 1 is fastened at a fixed location using a fastening tool 2. A locking groove 16a of a locking tube part 16 is inserted into an inner side annular gap 6 of a bolt head part 3 to match the position of a ball 10. Further, if an insertion tube part 15 is inserted into an outer side annular gap 8, the ball 10 is fixed in a ball holding bore 7a between the locking tube part 16 and the insertion tube part 15, and thereby the bolt 1 and the fastening tool 2 are locked. In this state, fastening operation of the bolt 1 can be performed by the fastening tool 2. Upon being fastened once, the bolt cannot be loosened without use of the fastening tool 2.