This paper presents the design and development of a bio-inspired legged rat robot, as an experimental tool for studying social interaction between rats and robots. The rat robot will be used as a platform to clarify basic factors for a relationship between rats and robots based on animal psychology and behavior. The developed rat robot has 4 legs with 3 DOF (2 active and 1 passive) for each leg. The two front legs are designed to perform simple manipulation tasks like pushing levers and buttons. Using our rat robot, an interaction experiment will be conducted to study the capability of the robotic rat to teach the real rat pushing levers