A vehicular impact absorber including: a hollow tubular body having a plurality of flat plate-shaped side walls and having a polygonal section; and a vehicle body-side attachment plate that is fixed integrally with the tubular body via a bracket in a state where the vehicle body-side attachment plate is in contact with one end portion of the tubular body in an axial direction, the vehicular impact absorber being fixed at the vehicle body-side attachment plate to a vehicle body-side member, and the vehicular impact absorber absorbing impact energy as the tubular body is crushed in the axial direction when an impact load is applied to the tubular body through the other end portion of the tubular body in the axial direction, the vehicular impact absorber being configured such that the bracket has a fixed plate portion that has a prescribed length in the axial direction of the tubular body.