This paper proposes a multi time scale behavior control method for autonomous omni-directional mobile robot. As for motion planning, there are many problems to solve such as pass planning for a goal, moving by obstacle avoidance, keeping away from danger, and so on. The method is based on virtual potential field method. For each problem having a time scale, the corresponding module is constructed and virtual potential field is generated. Virtual force calculated from each potential field is used for generating the velocity command. The numerical simulations were carried out to verify the usefulness of the proposed method. From the results, it was confirmed that the robot can reach the destination without colliding with the static and moving obstacles by using the proposed method.