In this paper, an analytical method is proposed to find the dimensions of impact stresses with using the dimensions of impact loading parameter regardless of mass of impactor, velocity of impactor, and plate thickness. In analytical method of impulsive stresses, the three-dimensional dynamic theory of elasticity using rectangular coordinates and the potential theory of displacement are utilized, and when the measurement of impact loading is difficult especially for a steel ball colliding on an infinite plate, the impact loading can be obtained by using the classical plate theory and Hertz`s contact theory. And in the numerical analysis, the fast Fourier transform (F. F. T.) algorithm and the numerical inverse Laplace transformation are used because the analysis of impact loading is difficult to obtain solutions by using the thress-dimensional dynamic theory of elasticity.