This paper describes a mechanism for a mastication robot using a human skull model. Since 1986 the authors have been developing the WJ (Waseda Jaw) series of mastication robots by using a dental study model, a duralumin mandibular, DC motors, wires, etc. From 1986 to 1991 the authors developed mastication robots with a mechanical mandibular model, and experimented with these robots. However, in order to analyze the human masticatory system, we needed a model closer to the human. The characteristics of the new mastication robot mechanism developed in 1992 are, that this robot has a structure similar to the human by using a skull model and, that the argument of the temporalis muscle force vector is variable by using two actuators. On the basis of this robot, we will be able to clarify and construct a quantitative and dynamic masticatory model for human mastication because it has human-like structures.