In this paper, dynamic FEM analyses on the impact injury mechanism of a human head were performed. The human head model was built up by the VOXEL approach(1), where 40 million parallelepiped elements were created with 433 slice CT images (512×512 pixels). The material of a human head is classified into 10 tissues such as a scalp, CSF, a skull, a brain, dura mater and so on. The original digital model was remodeled with 1.22 million elements in order to finish the analysis in a reasonable computational time by a PC cluster system. To check usability of the present model the dynamic behaviors of a human head subjected to impact loads on the forehead were conducted. The obtained results agree well with the cadaveric tests by Nahum. In the second analysis side impact loads were assumed for the head model. The large equivalent strain was observed in the central region of the brain as well as the region near the impacted point, where hemorrhage is often found in actual damaged human heads by impacts.