In this research, the relation between the acceptable part tolerances of a surface-to-surface short range ballistic missile (SRBM) and optimum rocket performance, which is called missile accuracy, is obtained. The effect of error surces like aiming error, mallaunch, moment of inertia, missile weight, center of mass, specific impulse, atmosphere specific density, drag force, thrust misalignment, fin malalignment, and wind on optimum rocket performance is simulated using the 6-degree-of-freedom flight simulation program. A computer program is written to compute the error budget and the effect of missile part tolerances of SRBM on missile accuracy. Finally, the most free acceptable part tolerances are determined based on the required missile accuracy and minimum production cost.