When a pressure wave of finite amplitude is generated in air by a rapid release of energy, such as high-pressure gas storage vessel or the blast from dynamite, there may be undetected brain injuries even though protective armors prevent the penetration of the projectile. To study brain tissue injury and design a better personnel head armor under blast wave, computational models of human head have been developed. Models with and without helmet are built to quantify the intracranial pressure and shear stresses of head subjected to blast wave. All the models are compared against injury thresholds for intracranial pressure and shear stresses. Overall pressure and shear stress level is highest in model without helmet and lowest in model with helmet having foam layer on inner side of helmet. The results show that helmet reduces the pressure and shear stresses generated in the brain. However this reduction in pressure and shear stresses might not be sufficient to mitigate early time, blast induced, traumatic brain injury. The validated results will provide better understanding of the energy transfer characteristics of blast wave through helmet and the injury mechanism of human head.