Internal organ's models have been studied for automatic needle insertion or a VR simulator that is used for surgical training. In this study, a puncture experiment was performed with the puncture device to examine the change of mechanical property between the tissue in-vivo and the excised tissue in mechanical property measurement experiments that are necessary to design the internal organ's model. In the experiments, a liver of the same pig was punctured in-vivo and in-vitro, and the applied force to the needle from the liver, the puncture depth and the puncture speed are measured to examine the change of the organ's property. In in-vitro experiments, the change of the organ's property of the elapsed time after the animal was euthanized was also examined. The experimental results showed that the amount of the puncture forces of the liver in-vitro were about twice larger than those of the liver in-vivo. The puncture displacements at the moment of piercing the surface of the liver in-vivo and in-vitro were almost the same. The parameters of the Kelvin Boltzmann model for excised tissue indicated higher value than those of in-vivo. These results suggested that there is a difference in properties between the tissue in-vivo and the excised tissue and careful consideration is required in the modeling.