In this paper, we introduce a passive mobile robot called PRP (Passive Robot Porter), which has passive dynamics with respect to an applied force and its appropriate motion is controlled based on the servo brakes. This paper especially focuses on a motion control algorithm of multiple passive mobile robots for handling a single object in cooperation with a human. By controlling each passive mobile robot in the decentralized way, we realize several kinds of motion characteristics of the object to improve the maneuverability for the human operator. By changing the apparent dynamics of the representative point of the object and its position, we realize an anisotropic apparent motion characteristic of the handling object and the obstacle avoidance function as examples. The proposed motion control algorithms are implemented to two PRPs actually, and experimental results illustrate the validity of the proposed algorithms.