The authors carried out theoretical investigations into the impulsive pressure acting on elastic structures. In the paper, the following two items are mainly discussed; (1) On the distribution of impulsive pressure acting on elastic structures induced by compression of fluid. (2) On the possibility of calculation of the deformation of elastic structures using simple dynamic model without considering the strict dynamic behavior of the impulsive pressure. The following conclusions were obtained : (1) When the impulse on the fluid is cushioned by the likes of a spring, the impulsive pressure is distributed uniformly except some special cases. On the other hand, when the impulse is not cushioned, the pressure is not distributed uniformly by the occurence of pressure of sound wave. (2) When the natural period of the structure is less than the duration of the impulsive pressure, the reasonable elastic deformation can be estimated by an proper approximate method.