The motions of a hammer are commonly regarded as a circular movement which a hammer undergoes around a turning human body. The distance of a throw depends on the speed of the hammer and the angle of its trajectory at the instant of release. The speed of the hammer increases gradually during preliminary winds and turns. During each turn the hammer rises up toward the high point of the trajectory and passes through the low point. Our interest in this study was to understand the mechanism of acceleration of the hammer in terms of parametrical excitation. The motions of hammer were analyzed to examine our theory using double pendulum model.