Simulation of the biting action of the gorilla was made by using a macerated skull of the gorilla. Strains in the facial skeleton produced by this simulation were measured by the wire strain gauge. Some stress analyses were made from these strains and were compared with those of the human facial skeleton. The strains in the facial skeleton of the gorilla indicate fundamentally the same deformation during biting action as do those of the human facial skeleton, but differences between both facial skeletons also appear. Generally the force of the temporalis tends to strain the facial skeleton more compressively while the force of the masseter does so more tensilely. They produce qualitatively the same but quantitatively different strains or stresses.