In this paper, we propose a motion control algorithm for handling a single object by multiple mobile manipulators in coordination with a human. In this algorithm, the representative point of each robot is controlled as if it was a caster-like dynamics in 3D space so that robots could manipulate an object without using the information of the object size and the geometric relation between robots. In addition, singular points of the manipulator are decreased in this control algorithm so that we could handle the object extensively in 3D space.