Many fatal accidents due to falling from height have happened at construction sites in Japan. The purpose of this study is about to understand the fundamental prevention performances of safety belts due to falling. Simply drop tests were carried out to measure impact load and posture of human dummy by using a Hybrid III pedestrian model and a sandbag. After that, the human injury probability and a magnitude of the impact force were discussed by comparing with each experimental results. These results suggest needs to reduce fall energy by using some shock absorber and so for serious injuries prevention.