Surgical robot has been considerable improvement in recent years, but their intuitive operability, representing user interoperability, has yet to be quantitatively evaluated. Thus, we propose a method for measuring brain activity to determine intuitive operability so as to design a robot with intuitive operability. The objective of this paper is to determine the angle and radius between the endoscope and the manipulator that allows users to perceive the manipulator as part of their body. In the experiments, subjects moved the hand controller to position the tip of the virtual slave manipulator on the target in the surgical simulator, measured the brain activity through brain imaging devices. The experiment was carried out a number of times with the virtual slave manipulator configured in a variety of ways. The results show that brain activation is significantly greater with a particular slave manipulator configuration. It concludes that the hand-eye coordination between the body image and the robot should be closely matched in the design of a robot with intuitive operability.