Embodiment of robots and computers are very similar to humans, and viewers in suspense. This is the “uncanny valley” effect. One hypothesis for this effect, the real composite is similar to human evoke the notion of a human, it is because the lack of healthy human image, in the evolution of human attempts to avoid such unhealthy developed to describe the resulting emotions. This time, in order to verify whether the emotions have evolutionary origins of this instability, in the monkey “uncanny valley” effect occurs whether or not examined. 1) monkey face was unrealistic synthesis, 2) a composite face is real, and 3) the actual face of the monkey showing the three types of monkey’s face at the same time, I like to see how the monkey’s face the decision by the time you see someone that is presented. Real face of a monkey than synthetic long face looked unrealistic and the actual face. This result, the sexual behavior of the monkey visual “mysterious valley,” indicating that the effect exists.