To improve installation workability of a long member such as a wire harness to a vehicle body.

This vehicular belt clamp is integrally provided with a belt 10, a buckle 20, and an anchor 30. The belt 10 is formed into a circular arc shape, is provided with a plurality of locking tooth 11 on its peripheral surface, is wound along a circular arc, and is wound around the long member. The buckle 20 is integrally formed with the base end of the belt 10, and has an introducing path T for introducing the end of the belt 10 on the base end side of the belt 10. The buckle 20 is provided with a locking portion 21a lockable with the locking tooth 11 on the belt 10. With the belt 10 wound around the long member, the locking tooth 11 are locked by the locking portion 21a, thereby the belt 10 is prevented from being rewound in a direction where the circular arc diameter of the belt 10 is increased.