In order to investigate the effects of ball structure on spin rate of golf ball, impact phenomena between a golf club head and a golf ball was simulated by the finite element method. As results, the following two points are obtained. Firstly, spin rate gets maximum value at a certain coefficient of friction in any loft angle of club head and is affected by ball structure through the larger coefficient of friction then the certain coefficient of friction. Secondly, spin rate depends on the distribution shape of Young's modulus on radial direction, and a larger ratio of outside to inside rigidity of ball causes a smaller spin rate. That is, it is considered that the distribution shape of rigidity is dominant to the reverse time of tangential force.