Recently, bio-robotics which based on robotics and biology, and neuro-robotics which based on robotics and neuroscience have been attracting big attention. In both of them, many studies have been conducted referring to studies on animal behavior which have been performed by animal psychologists and biologists. An autonomous, robotic experimental setup was then developed for the experiments to investigate behavior of rodents especially rats in "open-field". This setup consists of a square open-field surrounded by walls, a CCD camera above the open-field, a food feeding machine, a water feeding machine, sensors which measures rearing, sensors which measures grooming and a PC to autonomously control these machines and sensors. Grooming and rearing are typical behavior of rats, and rats' current emotional state can be understood by the numbers of these behaviors. Therefore, this experimental setup can be useful to study rats' emotion based on behavior analysis. Several experiments will be performed using this setup and it is expected that this setup contribute to studies on behavior and emotion model of rodents.