To provide a clamp for preventing the fall-off of a nut from a bolt.

One end of a first clamping member 41 is connected to one end of a second clamping member 42 so as to be turnable via a connection member 43. The nut 48 is threaded to the bolt 46 whose base end is connected to the other end of the first clamping member 41 so as to be turnable. Relative to the bolt 46 inserted into a U-shaped cut-out portion formed at the other end of the second clamping member 42, the second clamping member 42 is turned around the connection member 43 by the pressing operation of the nut 48 when rotated. Thereby, a clamped member 3 is clamped by the first clamping member 41 and the second clamping member 42. At the tip of the bolt 46 on the opposite side to the base end, a nut stop portion 52 is arranged by the installation or the like of a stop member 53 for preventing the fall-off of the nut 48 from the bolt 46.