This paper proposes a distributed algorithm for circle formation by multiple autonomous mobile robots with limited visibility. Each robot sees up to a fixed distance around it and moves to a new position. Eventually they form a circle of a given radius. The robots do not store past actions. The robots are anonymous and cannot be distinguished by their appearances. All robots agree upon a common origin and axis. Earlier works report algorithms for gathering of multiple autonomous mobile robots in limited visibility considering the robots to be dimensionless or points. This paper considers a robot as an unit disc (fat robot). The algorithm presented in this paper also assured to prevent collision among fat robots. The robots execute the algorithm asynchronously.