Acknowledgements This research was supported in part by the National Institute of Information and Communications Technology. In most applications of virtual environments, such as training or visual simulations, users need a good sensation of locomotion. We have developed several prototypes of interface devices for walking since 1989. From the results of this research, we determined that an infinite surface is an ideal device for creating a sense of walking. We employ a group of omni-directional movable floors to realize the locomotion interface. Each floor is equipped with a holonomic mechanism that achieves omni-directional motion. An infinite surface is simulated by circulation of the movable floors. The position of each floor is detected by ultra-sound sensors.The motion of the feet is measured by magnetic sensors. The floor moves opposite to the measured direction of the walker, so that motion of the step is canceled. The position of the walker is fixed in the real world by this computer-controlled motion of the floors. The circulation of the floors has an ability to cancel the displacement of the walker in arbi t rary direction. Thus, the walker can freely change direction while walking. CirculaFloor is a locomotion interface using a group of movable floors. The movable floors employ a holonomic mechanism that achieves omni-directional motion. Circulation of the floors enables the user to walk in a virtual environment while his/her position is maintained. The user can walk in arbitrary directions in a virtual environment.