It is a key point for simulation studies of medical problems on spine to construct the musculo-skeletal model of spine. The skeletal model has been constructed from the computed tomography images of a young healthy male. The muscles, disks and ligaments are attached to the skeletal model. The placement and mechanical properties are defined by established data of the literatures. The simulations of spinal motions have been performed with the constructed model to analyze the dynamics and vertebral stress distributions. It is shown by comparing the results to actual observations that the proposed musculo-skeletal model of spine is useful to simulate the dynamic spinal motions and to estimate the stress distributions on bones of spine.