A vehicle shock absorber by which a uniform shock absorbing property can be obtained in all positions on a shock receiving surface and, particularly, a further uniform shock absorbing property can be obtained if the distance from the lower end of a recessed groove in a first wall to a second wall is made equal to the distance from the lower end of the recessed groove in the first wall to the lower end of a recessed groove in the second wall. A vehicle shock absorber (1) is installed inside a vehicle component part so as to absorb shocks from interior or exterior. The vehicle shock absorber (1) is formed hollow by blow-molding thermoplastic plastic. A first wall (2) and a second wall (3) are spaced from and opposed to each other. A shock receiving surface (4) connects the first and second walls (2, 3). The first and second walls (2, 3) are formed with pluralities of recessed grooves (5, 6) at substantially equally spaced intervals. The recessed grooves (5, 6) are disposed substantially normal to the shock receiving surface (4).