In order to minimize occupant injury in a vehicle crash, an approach was attempted to address this issue by making the wave form of vehicle body deceleration (deceleration curve) optimal to lower the maximum deceleration value applied to the occupant. A study with a one-dimensional, two-mass model was conducted to the kinetic mechanism between the body deceleration curve and the responding occupant''s motion while finding a mathematical solution for the optimal body deceleration curve. A common feature of the derived mathematical solutions is that they consist of three aspects: high deceleration, low or negative deceleration, and constant deceleration. This was demonstrated by simulation with a three-dimensional dummy. The results show that the response of the dummy closely agrees with that of the one-dimensional, two-mass model, thus proving the adequacy of the mathematical solution, and that occupant injury was reduced. By varying the parameters of the mathematical solution, a consistent explanation was also found for the optimum vehicle deceleration curve obtained by the sensitivity analysis. This has made it possible to generalize the optimum vehicle deceleration curve. A type of new body construction is proposed to generate the optimal body deceleration curve by utilizing the differences in the load characteristics in relation to the deformation mode. An application was tested in a production vehicle to modify the vehicle deceleration curve by using the method based on the proposed construction, and the occupant injury criteria were successfully reduced.