The heat transfer at the workpiece-dic interface is controlled by thermal interface resistance. In the cases of dry contact or mixed lubrication. one speaks about thermal contact resistance (TCR). During hot forging, the workpiece-die contact is not static since the normal stress at the interface monotonously increases as the forging force. In this paper, the assumption of TCR in the case of the workpiece-die interface during the hot forging process is validated experimentally. The experiment shows that the TCR depends only on the instantaneous strain, which makes it an intrinsic parameter related to the instantaneous structure of the interface and not to the forging time. The significant role of the constitutive law of the workpiece on the evolution of the TCR is also shown.