Abstract: A vehicle impact attenuator that can be installed at low cost in a narrow installation space, immediately stop a colliding vehicle, and effectively mitigate the impact on the vehicle. The vehicle impact attenuator includes a shock absorber that deforms upon a collision by a vehicle to reduce the impact on the vehicle. A support is provided for the shock absorber and a holding portion holds the support (20A) in a vertical position in an installation area. The support has cuts made in it that upon application of a load equal to or exceeding a set value, fracture and function as a release mechanism to thereby release the support from being held in a vertical position in the installation area. The support is deformable by a load less than the set value.